Disable tests failing on amazon linux

[jmschonfeld]

These tests are failing on amazon linux with:

Test Case 'TestDateFormatter.test_setTimeZoneToNil' started at 2024-07-30 02:30:52.313
TestFoundation/TestDateFormatter.swift:337: error: TestDateFormatter.test_setTimeZoneToNil : XCTAssertEqual failed: ("Optional(GMT)") is not equal to ("Optional(Etc/UTC)") - 
TestFoundation/TestDateFormatter.swift:340: error: TestDateFormatter.test_setTimeZoneToNil : XCTAssertEqual failed: ("Optional(GMT)") is not equal to ("Optional(Etc/UTC)") - 
Test Case 'TestDateFormatter.test_setTimeZoneToNil' failed (0.0 seconds)
Test Case 'TestTimeZone.test_systemTimeZoneUsesSystemTime' started at 2024-07-30 02:30:03.140
TestFoundation/TestTimeZone.swift:167: error: TestTimeZone.test_systemTimeZoneUsesSystemTime : XCTAssertEqual failed: ("GMT") is not equal to ("UTC") - expected name "UTC" is not equal to "GMT"
Test Case 'TestTimeZone.test_systemTimeZoneUsesSystemTime' failed (0.0 seconds)

Let's disable these tests to unblock CI while we investigate

[jmschonfeld]

@swift-ci please test