GHA: reduce total timeouts for Linux and macOS jobs

- Linux: 25 -> 15 minutes.
- Linux H3: 45 -> 10 minutes.
- macOS: 25 -> 15 minutes.

On macOS this may catch flaky slowness seen sometimes in pytests:
https://github.com/curl/curl/pull/20187#issuecomment-3711753097

Closes #20192

.github/workflows/http3-linux.yml

@@ -345,7 +345,7 @@ jobs:
     needs:
       - build-cache
     runs-on: 'ubuntu-latest'
-    timeout-minutes: 45
+    timeout-minutes: 10
     env:
       MATRIX_BUILD: ${{ matrix.build.generate && 'cmake' || 'autotools' }}
       MATRIX_INSTALL_PACKAGES: '${{ matrix.build.install_packages }}'

.github/workflows/linux.yml

@@ -66,7 +66,7 @@ jobs:
     name: ${{ matrix.build.generate && 'CM' || 'AM' }} ${{ matrix.build.name }}
     runs-on: ${{ matrix.build.image || 'ubuntu-latest' }}
     container: ${{ matrix.build.container }}
-    timeout-minutes: 25
+    timeout-minutes: 15
     env:
       MATRIX_BUILD: ${{ matrix.build.generate && 'cmake' || 'autotools' }}
       MATRIX_INSTALL_PACKAGES: '${{ matrix.build.install_packages }}'

.github/workflows/macos.yml

@@ -207,7 +207,7 @@ jobs:
   macos:
     name: "${{ matrix.build.generate && 'CM' || 'AM' }} ${{ matrix.build.compiler }} ${{ matrix.build.name }}"
     runs-on: 'macos-15'
-    timeout-minutes: 25
+    timeout-minutes: 15
     env:
       DEVELOPER_DIR: "/Applications/Xcode${{ matrix.build.xcode && format('_{0}', matrix.build.xcode) || '' }}.app/Contents/Developer"
       CC: '${{ matrix.build.compiler }}'