[hud] Match viable/strict-blocking jobs on workflow name, not substring (#8439)

Stack from [ghstack](https://github.com/ezyang/ghstack/tree/0.15.0)
(oldest at bottom):
* __->__ #8439

isJobViableStrictBlocking used unanchored substring regexes, so "trunk"
matched "trunk-tagging" / "trunk-rocm-sandbox" and mislabeled them as
viable/strict blocking (shown even with "Hide non-viable-strict jobs").
Anchor patterns to the workflow-name segment to mirror the gate.

Test: yarn jest test/jobClassifierUtil.test.ts

Author: georgehong

torchci/lib/JobClassifierUtil.ts

@@ -9,12 +9,15 @@ type RepoViableStrictBlockingJobsMap = {
 
 // Source of truth for these jobs is in https://github.com/pytorch/pytorch/blob/main/.github/workflows/update-viablestrict.yml#L26
 export const VIABLE_STRICT_BLOCKING_JOBS: RepoViableStrictBlockingJobsMap = {
+  // Patterns match the workflow-name segment (before the first " / "), so
+  // "trunk" does not match "trunk-tagging" / "trunk-rocm-sandbox". "(L4)" is a
+  // config-token match, not a workflow name.
   "pytorch/pytorch": [
-    /pull/i,
-    /trunk/i,
-    /lint/i,
-    /linux-aarch64/i,
-    /docs-build/i,
+    /^pull($| \/)/i,
+    /^trunk($| \/)/i,
+    /^lint($| \/)/i,
+    /^linux-aarch64($| \/)/i,
+    /^docs-build($| \/)/i,
     /\(L4\)/,
   ],
 };

torchci/test/jobClassifierUtil.test.ts

@@ -59,6 +59,12 @@ describe("isJobViableStrictBlocking", () => {
     ["Lint / lintrunner", true],
     ["some-random-job", false],
     [", mem_leak check", false],
+    // "trunk" must not match differently-named workflows that share the prefix.
+    [
+      "trunk-rocm-sandbox / linux-noble-rocm-py3.12-mi300 / test (default)",
+      false,
+    ],
+    ["trunk-tagging / tag", false],
   ])("pytorch/pytorch %j -> %s", (jobName, expected) => {
     expect(isJobViableStrictBlocking(jobName, "pytorch", "pytorch")).toBe(
       expected