Update dynamic parallel logic for TEST_TIME

In dynamic parallel mode, the user-defined TEST_TIME is automatically overridden if any test exceeds that duration (t > TEST_TIME). In such cases, TEST_TIME is updated to match the longest test duration (t). The workload is then split based on this new TEST_TIME to maximize throughput. However, this can lead to significantly longer build times. For example, in the following, what should be 2-hour builds are turning into 4-hour builds, and in one case, even 17-hour builds.

We should update the logic to use the original TEST_TIME value (regardless of test duration).

```
00:04:54.684 TEST DURATION
00:04:54.684 ====================================================================================
00:04:54.684 Total number of tests searched: 431
00:04:54.684 Number of test durations found: 417
00:04:54.684 Top slowest tests:
00:04:54.684 251m50s SPECjbb2015_2
00:04:54.684 206m45s SPECjbb2015_3
00:04:54.684 81m14s SPECjbb2015_0
00:04:54.684 Following test duration data cannot be found:
00:04:54.684 (Default duration assigned, executed tests: 40s; not executed tests: 0s.)
00:04:54.684 [cmdLineTester_jvmtitests_Java11andUp_4, cmdLineTester_jvmtitests_Java11andUp_5, cmdLineTester_jython_7, cmdLineTester_jython_8, cmdLineTester_jython_9, cmdLineTester_jython_10, cmdLineTester_DataHelperTests_2, cmdLineTester_DataHelperTests_3, testSCCMLTests1_openj9_2, testSCCMLTests1_openj9_3, testSCCMLListALLCaches_2, testSCCMLListALLCaches_3, testSCCMLExpireAndListALLCaches_1, testSCCMLExpireAndListALLCaches_2]
00:04:54.684 ====================================================================================
00:04:54.684 Warning: Test SPECjbb2015_2 has duration 251m50s, which is greater than the specified test list execution time 7200000m. So this value is used to limit the overall execution time.
```

[link](https://hyc-runtimes-jenkins.swg-devops.com/job/Test_openjdk17_j9_sanity.functional_x86-64_windows/881/consoleFull)