Fix: Environment-agnostic TimeZone formatting in TestPureDate

[kapilhadoltikar]

Bug Report

Steps to Reproduce:

1. Clone the legend-engine repository.
2. Navigate to the legend-engine-executionPlan-execution module.
3. Execute the Maven test suite using the command: mvn clean test -Dtest=TestPureDate.
4. Observe the test failure in the testFormatWithTimeZoneShift method.

Expected Result:

The test should pass
BUILD SUCCESS without any assertion errors, confirming that the date-time string is formatted correctly with the expected timezone abbreviation (e.g., CST).

Actual Result:

The test fails because the date-time string is formatted using a GMT offset instead of the short ID:

[INFO] Results:
[INFO]
[ERROR] Failures:
[ERROR]   TestPureDate.testFormatWithTimeZoneShift:71 expected:<...-12-31 19:01:01.070 [CST]> but was:<...-12-31 19:01:01.070 [GMT-06:00]>
[INFO]
[ERROR] Tests run: 15, Failures: 1, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] -----------------------------------------------------------------------
-

Environment:

1. Project version/build: 4.122.1-SNAPSHOT
2. OS and runtime versions: Windows 11, OpenJDK Temurin 11.0.30 , Maven 3.9.11
3. Virtualised environment: None

Proposed Solution:

The failure is caused by the JDK's switch to the CLDR (Unicode Common Locale Data Repository) as the default locale provider, which sometimes formats the z pattern as a GMT offset instead of a short ID.

I propose updating the assertion in testFormatWithTimeZoneShift to accept both the short ID (e.g., CST) and the GMT offset (e.g., GMT-06:00). This ensures the test remains environment-agnostic while still validating the correct time-shift logic.

I intend to submit a Pull Request for this immediately.