ci: remove validate-do-not-submit check

This uses  `git merge-base --fork-point master` which currently is not yielding a SHA on the patch branch. In some cases merge-base will not working as expected when base is ahead. See https://public-inbox.org/git/xmqq375okvxy.fsf@gitster.mtv.corp.google.com/T/#r3830f032d76f39b82d0ffe7f8bd77351cf634d29

This validation checks if `DO_NOT_SUBMIT` string literal has been added using `git diff`, when present validation will fail.

This check is unneeded as we do not use the `DO_NOT_SUBMIT` pattern, as we typically use `wip!` commit message types.

(cherry picked from commit ab84fc5)

Author: alan-agius4

scripts/validate-do-not-submit.ts

@@ -11,7 +11,6 @@ import { execSync } from 'child_process';
 import templates from './templates';
 import validateBuildFiles from './validate-build-files';
 import validateCommits from './validate-commits';
-import validateDoNotSubmit from './validate-do-not-submit';
 import validateLicenses from './validate-licenses';
 import validateUserAnalytics from './validate-user-analytics';
 
@@ -48,11 +47,6 @@ export default async function (options: { verbose: boolean }, logger: logging.Lo
         || error;
   }
 
-  logger.info('');
-  logger.info(`Running DO_NOT${''}_SUBMIT validation...`);
-  error = await validateDoNotSubmit({}, logger.createChild('validate-do-not-submit')) != 0
-       || error;
-
   logger.info('');
   logger.info('Running license validation...');
   error = await validateLicenses({}, logger.createChild('validate-commits')) != 0