test-lib: retire "lint harder" optimization hack

test-lib: retire "lint harder" optimization hack

`test_run_` in test-lib.sh "lints" the body of a test by sending it down
a `sed chainlint.sed | grep` pipeline; this happens once for each test
run by a test script. Although this pipeline may seem relatively cheap
in isolation, it can become expensive when invoked 26800+ times by `make
test`, once for each test run, despite the existence of only 16500+ test
definitions across all tests scripts.

This difference in the number of tests defined in the scripts (16500+)
and the number of tests actually run by `make test` (26800+) is
explained by the fact that some test scripts run a very large number of
small tests, all driven by a series of functions/loops which fill in the
test bodies. This means that certain test definitions are being linted
repeatedly (tens or hundreds of times) unnecessarily. To avoid such
unnecessary work, 2d86a96220 (t: avoid sed-based chain-linting in some
expensive cases, 2021-05-13) added an optimization hack which allows
individual scripts to manually suppress the unnecessary repeated linting
of the same test definition.

However, unlike chainlint.sed which checks a test body as the test is
run, chainlint.pl checks each test definition just once, no matter how
many times the test is run, thus the sort of optimization hack
introduced by 2d86a96220 is no longer needed and can be retired.
Therefore, revert 2d86a96220.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>