Change default ml timeline buffer size to 192K

[Xlnx78115]

Problem solved by the commit

Since the size of cycle value in record_timer_ts.json is changed from from 32bit to 64bit, which will cause the alignment issue when the buffer is overwritten. This commit could resolve this alignment issue.

Bug / issue (if any) fixed, which PR introduced the bug, how it was discovered

PR8416 introduces this bug. In the test case, generated record_timer_ts.json contains the wrong records.

How problem was solved, alternative solutions (if any) and why they were rejected

Set size value of a multiple of 12K would make the buffer is aligned when it's full. In this case, the issue disappears.

Risks (if any) associated the changes in the commit

What has been tested and how, request additional testing if necessary

Run test and make sure the buffer is overwritten, then the alignment caused wrong result in record_timer_ts.json has gone. It means that this commit resolve this issue.

Documentation impact (if any)