CI(neon-extra-builds): Use small-arm64 runners instead of large-arm64 (#7740)

## Problem
There are not enough arm runners and jobs in `neon-extra-builds` workflow
take about the same amount of time on a small-arm runner as on
large-arm.

## Summary of changes
- Switch `neon-extra-builds` workflow from `large-arm64` to
`small-arm64` runners

.github/actionlint.yml

@@ -5,6 +5,7 @@ self-hosted-runner:
     - large
     - large-arm64
     - small
+    - small-arm64
     - us-east-2
 config-variables:
   - REMOTE_STORAGE_AZURE_CONTAINER

.github/workflows/neon_extra_builds.yml

@@ -136,7 +136,7 @@ jobs:
   check-linux-arm-build:
     needs: [ check-permissions, build-build-tools-image ]
     timeout-minutes: 90
-    runs-on: [ self-hosted, large-arm64 ]
+    runs-on: [ self-hosted, small-arm64 ]
 
     env:
       # Use release build only, to have less debug info around
@@ -260,7 +260,7 @@ jobs:
   check-codestyle-rust-arm:
     needs: [ check-permissions, build-build-tools-image ]
     timeout-minutes: 90
-    runs-on: [ self-hosted, large-arm64 ]
+    runs-on: [ self-hosted, small-arm64 ]
 
     container:
       image: ${{ needs.build-build-tools-image.outputs.image }}