Run fewer redundant rust formatting checks

We have no ARM64 or x64 specific code currently, so there's not much
need to run clippy and other rust codestyle checks on both
architectures. The check-codestyle-rust job took about 40 minutes on
arm64 in the CI, which is now avoided.

Also, skip running clippy in --release mode. It's pretty expensive to
run, and there is very little difference between debug and release
builds that could lead to different clippy warnings. The debug and
release clippy checks took about 6 minutes each, so this saves another
6 minutes of runtime on CI.

This doesn't make the overall CI runtime shorter, because other jobs
still take longer than thesee did. But the 40 minutes spent on arm64
was actually pretty close to being the slowest job, and spending less
on these tests is good anyway.

.github/workflows/build_and_test.yml

@@ -122,9 +122,11 @@ jobs:
 
   check-codestyle-rust:
     needs: [ check-permissions, build-build-tools-image ]
+    # There's no reason to expect clippy or code formatting to be different on different platforms,
+    # so it's enough to run these on x64 only.
     strategy:
       matrix:
-        arch: [ x64, arm64 ]
+        arch: [ x64 ]
     runs-on: ${{ fromJson(format('["self-hosted", "{0}"]', matrix.arch == 'arm64' && 'small-arm64' || 'small')) }}
 
     container:
@@ -168,8 +170,6 @@ jobs:
           echo "CLIPPY_COMMON_ARGS=${CLIPPY_COMMON_ARGS}" >> $GITHUB_ENV
       - name: Run cargo clippy (debug)
         run: cargo hack --feature-powerset clippy $CLIPPY_COMMON_ARGS
-      - name: Run cargo clippy (release)
-        run: cargo hack --feature-powerset clippy --release $CLIPPY_COMMON_ARGS
 
       - name: Check documentation generation
         run: cargo doc --workspace --no-deps --document-private-items