[IMP][FIX] test_mail: correctly simulate email send in performance tests
[IMP][FIX] test_mail: correctly simulate email send in performance tests

Commit 356a42166082f9448b7e82393caeb00839be8c8f introduced a hook to avoid sending emails while
installing application data. However we have to carefully re-activate email
sending in tests that depend on them especially performance tests.

This commit also update performance counters to match the current state of
counters as it was not totally updated.

Commit linked to task ID 1902307.
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