pw_presubmit: Fix bug in sanitizer presubmit
pw_presubmit: Fix bug in sanitizer presubmit

Actually run (don't just build) the sanitizer tests, so that
`pw presubmit --step runtime_sanitizers` has a chance of catching
any bugs. Needless to say, this exposes a bunch of failures. I'm slowly
triaging them.

Bug: 514
No-Docs-Update-Reason: Minor bugfix
Change-Id: I67860b1eda68783b6b5504407698fa21fb30acf9
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/67080
Reviewed-by: Rob Mohr <d07614a8a0b466db08f68224f87d738b0f9615cf@google.com>
Commit-Queue: Ted Pudlik <c7372cc3e451acc046049fca9e050bcb2a4a3d11@google.com>

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