all.bash: switch npm to run_npm in scripts

Using run_npm instead of npm directly in bash scripts.
This will default to local npm when available but use
docker-ized npm when the npm command is not found on
the host machine.

Change-Id: I08c0e69c5f18a29059eaf4787bc03d8eba99562b
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/311349
Trust: Jamal Carvalho <jamal@golang.org>
Run-TryBot: Jamal Carvalho <jamal@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Julie Qiu <julie@golang.org>

all.bash

@@ -264,8 +264,8 @@ main() {
     "")
       standard_linters
       run_prettier
-      npm run lint
-      npm run test
+      run_npm run lint
+      run_npm run test
       runcmd go mod tidy
       runcmd env GO_DISCOVERY_TESTDB=true go test ./...
       runcmd go test ./internal/secrets
@@ -296,8 +296,8 @@ main() {
         run_prettier $pfiles
       fi
       if [[ $(filter "$files" 'content/static/**') != '' ]]; then
-        npm run lint
-        npm run test
+        run_npm run lint
+        run_npm run test
       fi
       runcmd go mod tidy
       runcmd env GO_DISCOVERY_TESTDB=true go test ./...