chore: tune postgres CI tests (#17756)

Changes:
- use a bigger runner for test-go-pg on Linux
- use a depot runner to run postgres tests on Windows
- use the same Windows ramdisk action for postgres tests as the one
currently used for in-memory tests
- put GOTMPDIR on a ramdisk on Windows
- tune the number of tests running in parallel on macOS and Windows
- use a ramdisk for postgres on macOS
- turn off Spotlight indexing on macOS
- rerun failing tests to stop flakes from disrupting developers

Results:
- test-go-pg on Linux completing in 50% of the time it takes to run on
main ([run on
main](https://github.com/coder/coder/actions/runs/14937632073/job/41968714750),
[run on this
PR](https://github.com/coder/coder/actions/runs/14956584795/job/42013097674?pr=17756))
- macOS tests completing in 70% of the time ([run on
main](https://github.com/coder/coder/actions/runs/14921155015/job/41916639889),
[run on this
PR](https://github.com/coder/coder/actions/runs/14956590940/job/42013102975))
- Windows tests completing in 50% of the time ([run on
main](https://github.com/coder/coder/actions/runs/14921155015/job/41916640058),
[run on this
PR](https://github.com/coder/coder/actions/runs/14956590940/job/42013103116))

This PR helps unblock https://github.com/coder/coder/issues/15109.

.github/actions/setup-go/action.yaml

@@ -26,13 +26,15 @@ runs:
         export GOCACHE_DIR="$RUNNER_TEMP""\go-cache"
         export GOMODCACHE_DIR="$RUNNER_TEMP""\go-mod-cache"
         export GOPATH_DIR="$RUNNER_TEMP""\go-path"
+        export GOTMP_DIR="$RUNNER_TEMP""\go-tmp"
         mkdir -p "$GOCACHE_DIR"
         mkdir -p "$GOMODCACHE_DIR"
         mkdir -p "$GOPATH_DIR"
+        mkdir -p "$GOTMP_DIR"
         go env -w GOCACHE="$GOCACHE_DIR"
         go env -w GOMODCACHE="$GOMODCACHE_DIR"
         go env -w GOPATH="$GOPATH_DIR"
-
+        go env -w GOTMPDIR="$GOTMP_DIR"
     - name: Setup Go
       uses: actions/setup-go@0a12ed9d6a96ab950c8f026ed9f722fe0da7ef32 # v5.0.2
       with: