ci: don't fail CI when Codecov upload fails on fork PRs

The three Codecov upload steps use fail_ci_if_error: true with a
token-gated upload (CODECOV_TOKEN). GitHub Actions withholds secrets
from pull requests opened from forks, so the upload step fails and
turns the whole CI run red for external contributors, regardless of
whether their actual changes pass.

This restores the behaviour intentionally set in #1857
("keep running even if codecov upload fails"), which was reverted by
fe1e8a9 ("Fix codecov v4 configuration"). Coverage uploads from
trusted (non-fork) runs still happen; they just no longer hard-fail CI.

Author: arimu1

.github/workflows/ci-tests.yml

@@ -89,7 +89,7 @@ jobs:
         if: ${{ matrix.step == 'unit' }}
         uses: codecov/codecov-action@e79a6962e0d4c0c17b229090214935d2e33f8354 # v6
         with:
-          fail_ci_if_error: true
+          fail_ci_if_error: false
         env:
           CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
 
@@ -231,7 +231,7 @@ jobs:
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@e79a6962e0d4c0c17b229090214935d2e33f8354 # v6
         with:
-          fail_ci_if_error: true
+          fail_ci_if_error: false
         env:
           CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
   release_test:
@@ -320,6 +320,6 @@ jobs:
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@e79a6962e0d4c0c17b229090214935d2e33f8354 # v6
         with:
-          fail_ci_if_error: true
+          fail_ci_if_error: false
         env:
           CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}