pw_env_setup: Remove "." from environment directory
pw_env_setup: Remove "." from environment directory

As long as the ".environment" directory is around keep using it, but if
it's deleted start using "environment".

Bug: b/227763851
Change-Id: I5c05373fe778313fb4308672ad8d90c03e52a11e
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/31763
Reviewed-by: Keir Mierle <69344103cc60b36d6e1fbdc31ce6504b2286c646@google.com>
Reviewed-by: Wyatt Hepler <cca3bedb37979eacd157a9bceb473582df8aea1e@google.com>
Commit-Queue: Rob Mohr <d07614a8a0b466db08f68224f87d738b0f9615cf@google.com>

google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed