chore: ignore local tsbuildinfo files in docker builds (#8492)

Local docker builds (with existing build artifacts) no longer work since
https://github.com/ChainSafe/lodestar/pull/8481 because the file
`packages/cli/tsconfig.build.tsbuildinfo` is copied to docker build
which causes typescript to skip the build, but we are not copying the
`lib` which means the whole build is missing (and not rebuilt). The
tsbuildinfo is usually part of `lib` which is why this was no issue
before.

I believe this happens because `"rootDir": "src"` was added to tsconfig,
there might be a different way to fix this but in general we don't want
to copy tsbuildinfo files into docker builds.

.dockerignore

@@ -67,5 +67,6 @@ docs/site
 **/dist
 *.log
 **/*.log
+**/*.tsbuildinfo
 .idea
 .tmp