ci: only run "lint" in "insiders" job

Problem:
The release pipeline is blocked on the lint task because of an
environment issue (there is not actually a git secret in the source
code, this test already passed CI).

  1) git-secrets
       sanity check it finds secrets:
      AssertionError [ERR_ASSERTION]: Expected values to be strictly equal:
      at Context.<anonymous> (src/testLint/gitSecrets.test.ts:125:16)

Solution:
Only run lint in "insiders" job. That allows the release pipeline to
proceed.

Followup to: 6057ef4

Author: justinmk3

buildspec/linuxTests.yml

@@ -45,8 +45,11 @@ phases:
         commands:
             - export HOME=/home/codebuild-user
             # TODO: run lint as a separate codebuild job.
-            - npm run testCompile
-            - npm run lint
+            - |
+                if [ "$VSCODE_TEST_VERSION" = 'insiders' ] ; then
+                    npm run testCompile
+                    npm run lint
+                fi
             - xvfb-run npm test --silent
             - VCS_COMMIT_ID="${CODEBUILD_RESOLVED_SOURCE_VERSION}"
             - CI_BUILD_URL=$(echo $CODEBUILD_BUILD_URL | sed 's/#/%23/g') # Encode `#` in the URL because otherwise the url is clipped in the Codecov.io site