Too much cache pressure in test_stat08

Test failure

ERROR: test_stat08.test_stat08.test_session_stats

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Traceback (most recent call last):

  File "C:\data\mci\174942b30da0a5b666c8ef3b03a7d284\wiredtiger\test\suite\wttest.py", line 328, in _callTestMethod

    method()

  File "C:\data\mci\174942b30da0a5b666c8ef3b03a7d284\wiredtiger\test\suite\test_stat08.py", line 77, in test_session_stats

    cursor[i] = self.entry_value

  File "C:\data\mci\174942b30da0a5b666c8ef3b03a7d284\wiredtiger\cmake_build\lang\python\wiredtiger\swig_wiredtiger.py", line 413, in __setitem__

    if self.insert() != 0:

_wiredtiger.WiredTigerRollbackError: WT_ROLLBACK: conflict between concurrent operations

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Ran 988 tests in 1500.050s

Link: https://evergreen.mongodb.com/task_log_raw/wiredtiger_rapid_release_branch_windows_64_unit_test_bucket07_636ab553c9ec4405bf32a299_22_11_08_20_00_19/0?type=T#L1996