Remove some files from the repo root

[jakebailey]

Fixes #51444

The only potentially scary thing here is the docker change; it requires buildkit, but that should work so long as all of our images are Linux-based (which they are).

This removes 5 files from the repo root.

[jakebailey]

@typescript-bot user test this

I think this is the docker one? Maybe?

[typescript-bot]

Heya @jakebailey, I've started to run the diff-based user code test suite on this PR at 01969f8. You can monitor the build here.

Update: The results are in!

[typescript-bot]

@jakebailey Here are the results of running the user test suite comparing main and refs/pull/51446/merge:

Everything looks good!

[jakebailey]

@typescript-bot user test this slower

[typescript-bot]

Heya @jakebailey, I've started to run the community code test suite on this PR at 01969f8. You can monitor the build here.

[jakebailey]

@typescript-bot user test this slower

[typescript-bot]

Heya @jakebailey, I've started to run the community code test suite on this PR at 01969f8. You can monitor the build here.

[jakebailey]

The long user task appears to be broken, but that seems to be unrelated to this PR. I can confirm from the logs that the docker stuff works as expected: https://typescript.visualstudio.com/TypeScript/_build/results?buildId=139770&view=logs&j=fd490c07-0b22-5182-fac9-6d67fe1e939b&t=7cc137c2-61f2-5d65-b5f8-0e03d1af3170&l=1057

#2 [internal] load .dockerignore
#2 sha256:4a4ed123b7937fef327b6f12d7babeb7c7a07d5a8af63a162e6f811bf52948b2
#2 transferring context: 2B done
#2 DONE 0.0s

#1 [internal] load build definition from Dockerfile
#1 sha256:e6e25f4c61172b287941e50a438f9a94a99c43b98323adec666262af669c5696
#1 transferring dockerfile: 932B 0.0s done
#1 DONE 0.1s

#4 [auth] library/node:pull token for registry-1.docker.io
#4 sha256:9d889029f2fe9cc4ecee8c32e4b6949103b3aa1f0c32d07372b8410ce7579e3e
#4 DONE 0.0s

#3 [internal] load metadata for docker.io/library/node:current
#3 sha256:a8f9e90e756db67758be7de595ae6d22761b7409621f0db40bca2c65d7f7f599
#3 DONE 0.3s

This is buildkit output, and it's finding the new paths for the dockerignore and Dockerfile correctly, so this change looks to be safe.