[Test][Time profiler] Fix test time checking

This test sometimes triggers failures during build testing. For instance, see:
https://lab.llvm.org/buildbot/#/builders/52/builds/10161, details: https://lab.llvm.org/buildbot/#/builders/52/builds/10161/steps/5/logs/FAIL__Clang__check-time-trace-sections_cpp .
AFAICT the time between driver calling and checking its time tracker output
is not guaranteed to be stable and small:
```
> head -2 check-time-trace-sections.cpp
// RUN: %clangxx -S -ftime-trace -ftime-trace-granularity=0 -o %T/check-time-trace-sections %s
// RUN: cat %T/check-time-trace-sections.json | %python %S/check-time-trace-sections.py
> clang -S -ftime-trace -ftime-trace-granularity=0 -o /tmp/check check-time-trace-sections.cpp
> cat /tmp/check.json | python check-time-trace-sections.py
> sleep 10
> cat /tmp/check.json | python check-time-trace-sections.py
'beginningOfTime' should represent the absolute time when the process has started
>
```
The attribute `beginningOfTime` was introduced here: https://reviews.llvm.org/D78030
One can change "10 sec" value to something longer, but I believe
it's enough just to check that `beginningOfTime` exists and is
not later than current time.

Differential Revision: https://reviews.llvm.org/D108625

clang/test/Driver/check-time-trace-sections.py

@@ -20,10 +20,8 @@ def is_before(range1, range2):
 beginning_of_time = log_contents["beginningOfTime"] / 1000000
 seconds_since_epoch = time.time()
 
-# Make sure that the 'beginningOfTime' is not earlier than 10 seconds ago
-# and not later than now.
-if beginning_of_time > seconds_since_epoch or \
-        seconds_since_epoch - beginning_of_time > 10:
+# Make sure that the 'beginningOfTime' is not later than now.
+if beginning_of_time > seconds_since_epoch:
     sys.exit("'beginningOfTime' should represent the absolute time when the "
              "process has started")