Removed the old dynamically allocated GDMA channel approach.
It proved too unreliable as we couldn't not ensure consumers of the mbedtls
would properly free the channels after use.
Replaced by a single shared GDMA channel for AES and SHA, which won't be
released unless user specifically calls API for releasing it.
Enable shared stack watchpoint for overflow detection
Enable unit tests:
* "test printf using shared buffer stack" for C3
* "Test vTaskDelayUntil" for S2
* "UART can do poll()" for C3
Also simplified the labels and ci
- Remove label regular_test, weekend_test
- Remove apply_job_filter
- check_submodule_sync: only run on protected branch
