Background

After T1-T4, no test waits on the absolute failpoint counter by accident. But nothing stops someone from writing fpb->waitForTimesEntered(1) again in the future.

What to do

Change FailPoint::waitForTimesEntered so that absolute waits can't be written by accident. Evaluate three options and pick one:

• (a) require an explicit AbsoluteEntryCount{n} wrapper type

• (b) make the method private, reachable only through FailPointEnableBlock
• (c) rename it to waitForAbsoluteTimesEntered

Done when

• fpb->waitForTimesEntered(1) no longer compiles. If (c) is chosen, the old name no longer exists.
• The whole tree builds. The intentional uses in fail_point_test.cpp use the new spelling.
• The PR description compares (a), (b), and (c) and explains the choice.

Details

See attached pr5_restrict_absolute_api.md: the trade-offs of each option, which callers block option (b), and how to verify.