ci: Revert aarch64-linux timeout to GitHub's default 6 hours.

We don't seem to be getting non-deterministic hangs since 4f3b59f, and e28b402
cut the run times significantly on top of that. Runs now seem to take around 1-2
hours, so the default timeout should be plenty.

Author: alexrp

.github/workflows/ci.yaml

@@ -29,15 +29,13 @@ jobs:
       - name: Build and Test
         run: sh ci/x86_64-linux-release.sh
   aarch64-linux-debug:
-    timeout-minutes: 540
     runs-on: [self-hosted, Linux, aarch64]
     steps:
       - name: Checkout
         uses: actions/checkout@v4
       - name: Build and Test
         run: sh ci/aarch64-linux-debug.sh
   aarch64-linux-release:
-    timeout-minutes: 540
     runs-on: [self-hosted, Linux, aarch64]
     steps:
       - name: Checkout