perf test: Speed up test case 70 annotate basic tests

On some s390 linux machine (mostly older models) and with debug
packages installed, the test case 'perf annotate basic tests' runs
for some longer time.
Speed up the test and save the output of command perf annotate
in a temporary file. This is used to perform pattern matching via
grep command. This saves on invocation of perf annotate which
runs for some time.

Output before:
 # time bash -x tests/shell/annotate.sh >/dev/null 2>&1; echo EXIT CODE $?

 real   4m35.543s
 user   3m19.442s
 sys    1m14.322s
 EXIT CODE 0
 #
Output after:
 # time bash -x tests/shell/annotate.sh >/dev/null 2>&1; echo EXIT CODE $?

 real   2m2.881s
 user   1m30.980s
 sys    0m30.684s
 EXIT CODE 0
 #

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: gor@linux.ibm.com
Cc: hca@linux.ibm.com
Cc: sumanthk@linux.ibm.com
Cc: svens@linux.ibm.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240607054352.2774936-1-tmricht@linux.ibm.com