Clear testSuiteImplicitTests before adding tests

buildPartial can be called at least a second time in the event of a skyframe
restart (due to a missing dep) during package loading. This makes sure that
we don't double `$implicit_tests` when that happens.

PiperOrigin-RevId: 365136778

src/main/java/com/google/devtools/build/lib/packages/Package.java

@@ -1725,6 +1725,9 @@ private Builder beforeBuild(boolean discoverAssumedInputFiles) throws NoSuchPack
       }
 
       Collections.sort(tests); // (for determinism)
+      // In case we're called multiple times, as can happen in PackageFunction if skyframe deps are
+      // missing.
+      this.testSuiteImplicitTests.clear();
       this.testSuiteImplicitTests.addAll(tests);
 
       for (InputFile file : newInputFiles.values()) {