feat(scripts): add test:e2e:legacy:preview

[trivikr]

Issue

Internal JS-5464

Description

Adds a script for running legacy e2e tests only for preview builds.

Testing

Verified with changes prior v3.658.1 which impacted multiple clients:

• preview runs e2e tests only for the client being updated
• since:release runs e2e tests for all clients changed since last release

$ git checkout -b test 082bad80ae9bc56b83b787a7dad1ecc089dd7f4f

# Cherry pick changes from this PR
$ git cherry-pick 6643ed6^..cc02ac9

# Cherry pick changes in EC2 to process commit message
$ git cherry-pick 7fad22475a7768262a35854a0b30ec5ba11a2d36

# The preview runs e2e test only for the last changed package, i.e. ec2
$ yarn test:e2e:legacy:preview
yarn run v1.22.22
$ ./tests/e2e-legacy/preview.mjs
Updated scope: client-ec2
Running cucumber test: 
node_modules/.bin/cucumber-js --fail-fast -t "@ec2"
......................

5 scenarios (5 passed)
12 steps (12 passed)
1m53.451s (executing steps: 1m53.402s)
Done in 114.71s.

# The since:release runs e2e test for all changed packages
$ yarn test:e2e:legacy:since:release
yarn run v1.22.22
$ ./tests/e2e-legacy/since-release.mjs
Looking for changed packages...
lerna notice cli v5.5.2
lerna info Looking for changed packages since v3.658.0
lerna success found 413 packages ready to publish
Running cucumber test: 
node_modules/.bin/cucumber-js --fail-fast -t "@acm or @cloudformation or @cloudfront or @cloudtrail or @cloudwatch or @codecommit or @codedeploy or @codepipeline or @dynamodb or @ec2 or @ecr or @ecs or @efs or @elasticache or @emr or @gamelift or @glacier or @iam or @inspector or @iot or @kinesis or @kms or @lambda or @pinpoint or @rds or @redshift or @s3 or @sagemaker or @ses or @sns or @sqs or @ssm or @sts or @swf or @waf or @workspaces"
..............................................................................................................................................................................................................................................................................................................................................................................................................................................Are you using a Stream of unknown length as the Body of a PutObject request? Consider using Upload instead from @aws-sdk/lib-storage.
...........................................................................................................................................................................................................

103 scenarios (103 passed)
359 steps (359 passed)
3m37.179s (executing steps: 3m36.412s)
Done in 228.02s.

---

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.