This patch implements various improvements to the memory tests.
Memory tests are split off into separate workflow to allow running
them separately from prerelease tests by pushing to branch
memory_test. The scripts are adjusted to no longer build docker
images to run the tests but instead running the tests directly.
The python script to monitor memory usage was improved and now
flushes after printing to make output appear consistently in CI.
This patch also changes the memory test to run on PG 12,13 and 14
instead of only 12.
The memory leak job pulls TSDB dev tools from bitbucket but only two
files from that repository are needed.
This commit copy the files from the `tsdb-dev-tools` repository, remove
the need to clone the repository, update the memory leak job to use
these files, and remove the two secrets containing the environment
variables `USR` and `PASSWORD`.
