[flang][flang-omp-report] Remove the loop workarounds for nowait clause

In a "Worksharing-loop construct", one can add a nowait clause at the end
of the loop (i.e. at the loop tail). This clause wasn't associated with
the corresponding loop when originally worked on in flang-omp-report.
Note that this refers to parsing and parse-tree generation. To work
around it, it was needed to track such clauses and the loops.
This should no longer be required (and in fact no longer works) and so
was removed. This results in 'curLoopLogRecord' and 'loopLogRecordStack' and
all references to them being removed. This also allows for
'constructClauses' to be swapped from std::deque to llvm::SmallVector.
Lastly a new test has been added testing the "nowait" clauses in a
variety of ways.

Reviewed By: awarzynski, kiranchandramohan

Differential Revision: https://reviews.llvm.org/D112217