fix(ci): fix backport auto-label and skip fix(ci) from backport

[Yicong-Huang]

What changes were proposed in this PR?

The Backport Auto Label workflow crashed on every PR into main with Cannot find module '@actions/github': it built a second Octokit via require("@actions/github"), but github-script's require resolves from the checked-out workspace, which has no such package. Regressed in #6962.

Instead of github-script's __original_require__ escape hatch, this splits the single step into two, each with its own github-token, so no second Octokit is built in-script:

• Label (PAT): all reads and label writes, so a labeled event still retriggers the backport pre-merge check.
• Report (GITHUB_TOKEN): requests reviewers and upserts the report comment as github-actions[bot].

Also skips fix(ci): PRs — CI-only fixes are never backported. Behavior is otherwise unchanged.

Any related issues, documentation, discussions?

Closes #6969

How was this PR tested?

• node --check on both script bodies and a YAML parse of the workflow.
• This PR's own Backport Auto Label check stays red until merge: pull_request_target runs the base-branch (still-broken) workflow.

Was this PR authored or co-authored using generative AI tooling?

Generated-by: Claude Code (Claude Opus 4.8)

[github-actions]

Automated Reviewer Suggestions

Based on the git blame history of the changed files, we recommend the following reviewers:

• No candidates found from git blame history.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.96%. Comparing base (5040cad) to head (722f241).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6970      +/-   ##
============================================
- Coverage     78.97%   78.96%   -0.01%     
  Complexity     3783     3783              
============================================
  Files          1160     1160              
  Lines         46105    46105              
  Branches       5115     5115              
============================================
- Hits          36413    36409       -4     
- Misses         8068     8072       +4     
  Partials       1624     1624              

Flag	Coverage Δ
access-control-service	70.00% <ø> (ø)
agent-service	76.76% <ø> (ø)
amber	72.16% <ø> (-0.02%)	⬇️
computing-unit-managing-service	20.49% <ø> (ø)
config-service	66.66% <ø> (ø)
file-service	67.21% <ø> (ø)
frontend	82.99% <ø> (ø)
notebook-migration-service	78.94% <ø> (ø)
pyamber	95.34% <ø> (-0.05%)	⬇️
workflow-compiling-service	26.31% <ø> (ø)

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[github-actions]

✅ No material benchmark regressions detected

🟢 4 better · 🔴 0 worse · ⚪ 11 noise (<±5%) · 0 without baseline

Compared against main 5040cad benchmarked on this same runner, so the delta is largely free of cross-runner hardware noise. The "7d avg" column still reflects the gh-pages dashboard. Treat <±5% as noise unless repeated.

Dashboard · Run

	config	throughput	MB/s	latency	max Δ latest / 7d
🟢	bs=10 sw=10 sl=64	428	0.261	23,257/30,470/30,470 us	🟢 -9.0% / 🔴 +87.7%
🟢	bs=100 sw=10 sl=64	952	0.581	103,555/123,367/123,367 us	🟢 -10.9% / 🔴 +13.5%
⚪	bs=1000 sw=10 sl=64	1,100	0.671	913,228/962,156/962,156 us	⚪ within ±5% / 🟢 -10.7%

Baseline details

Latest main 5040cad from same runner

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	428 tuples/sec	429 tuples/sec	767.9 tuples/sec	-0.2%	-44.3%
bs=10 sw=10 sl=64	MB/s	0.261 MB/s	0.262 MB/s	0.469 MB/s	-0.4%	-44.3%
bs=10 sw=10 sl=64	p50	23,257 us	23,298 us	12,502 us	-0.2%	+86.0%
bs=10 sw=10 sl=64	p95	30,470 us	33,499 us	16,234 us	-9.0%	+87.7%
bs=10 sw=10 sl=64	p99	30,470 us	33,499 us	18,919 us	-9.0%	+61.1%
bs=100 sw=10 sl=64	throughput	952 tuples/sec	951 tuples/sec	974.8 tuples/sec	+0.1%	-2.3%
bs=100 sw=10 sl=64	MB/s	0.581 MB/s	0.58 MB/s	0.595 MB/s	+0.2%	-2.3%
bs=100 sw=10 sl=64	p50	103,555 us	104,475 us	102,449 us	-0.9%	+1.1%
bs=100 sw=10 sl=64	p95	123,367 us	138,428 us	108,652 us	-10.9%	+13.5%
bs=100 sw=10 sl=64	p99	123,367 us	138,428 us	116,310 us	-10.9%	+6.1%
bs=1000 sw=10 sl=64	throughput	1,100 tuples/sec	1,110 tuples/sec	1,004 tuples/sec	-0.9%	+9.6%
bs=1000 sw=10 sl=64	MB/s	0.671 MB/s	0.678 MB/s	0.613 MB/s	-1.0%	+9.5%
bs=1000 sw=10 sl=64	p50	913,228 us	903,451 us	999,606 us	+1.1%	-8.6%
bs=1000 sw=10 sl=64	p95	962,156 us	934,011 us	1,046,770 us	+3.0%	-8.1%
bs=1000 sw=10 sl=64	p99	962,156 us	934,011 us	1,076,937 us	+3.0%	-10.7%

Raw CSV

config_idx,batch_size,schema_width,string_len,num_batches,total_ms,total_tuples,total_bytes,tuples_per_sec,mb_per_sec,lat_p50_us,lat_p95_us,lat_p99_us
0,10,10,64,20,467.13,200,128000,428,0.261,23256.97,30470.44,30470.44
1,100,10,64,20,2101.24,2000,1280000,952,0.581,103554.65,123366.96,123366.96
2,1000,10,64,20,18184.61,20000,12800000,1100,0.671,913228.26,962155.95,962155.95