[Chapel Merge] Remove CHPL_NIGHTLY_CRON_RECIPIENT from the test scripts

Branch: refs/heads/main
Revision: f045784d181be75a69af7fa47d20f833a93ab306
Author: bhavanijayakumaran
Link: Remove CHPL_NIGHTLY_CRON_RECIPIENT from the test scripts by bhavanijayakumaran · Pull Request #23907 · chapel-lang/chapel · GitHub
Log Message:
Remove CHPL_NIGHTLY_CRON_RECIPIENT from the test scripts (#23907)

Address https://github.com/Cray/chapel-private/issues/5606
Remove nightly email env from the test script.
Reviewed by @tzinsky @riftEmber

Compare: Comparing d57c478818ec93aad600030e49bb318fe73e7bb0...ad2fa5515cb572556a694c772a99b17d01aa7dec · chapel-lang/chapel · GitHub

Diff:
M doc/rst/developer/bestPractices/NightlyTesting.rst
M util/buildRelease/testRelease
M util/cron/README
M util/cron/nightly
https://github.com/chapel-lang/chapel/pull/23907.diff