Follows-up I361fde0de7f4406bce6ed075ed397effa5be3359.
Per T253461, not mass-changing source code, but the use of the native
error silencing operator (@) is especially useful in tests because:
1. It requires any/all statements to be explicitly marked. The
suppressWarnings/restoreWarnings sections encourage developers to
be "lazy" and thus encapsulate more than needed if there are multiple
ones near each other, which would ignore potentially important
warnings in a test case, which is generally exactly the time when
it is really useful to get warnings etc.
2. It avoids leaking state, for example in LBFactoryTest the
assertFalse call would throw a PHPUnit assertion error (not meant
to be caught by the local catch), and thus won't reach
AtEase::restoreWarnings. This then causes later code to end up
in a mismatching state and creates a confusing error_reporting
state.
See .phpcs.xml, where the at operator is allowed for all test code.
Change-Id: I68d1725d685e0a7586468bc9de6dc29ceea31b8a
128debb64b