[MNG-8258] Change the fixed reproducible build outputTimestamp to 1 Feb 1980

[stokito]

JIRA Issue: MNG-8258
IT PR: apache/maven-integration-testing#392

---

The Maven used the own inception year 2001.
But the Gradle already use the 1 Feb 1980 for preserveFileTimestamps.

The 1 Jan 1980 is a minimal date in Zip archive but the 1 Jan has some special treatment by Java that's why the Gradle team used the 1 Feb.

See more detailed description in CONSTANT_TIME_FOR_ZIP_ENTRIES https://github.com/gradle/gradle/blob/master/platforms/core-runtime/files/src/main/java/org/gradle/api/internal/file/archive/ZipEntryConstants.java#L39

The change was first proposed in the #1726 (comment) and also slightly discussed in the MSHARED-1430

@hboutemy:
many people have many opinions: there are even more opinions than people
The default value has been added in MNG-8258 with a Maven-specific timestamp (no reason to try to mimic others: there is no perfect or wrong choice)
@stokito:
Sure, but a standardization always improves and simplifies things (if done right). Having the same value 1 Feb 1980 will simplify search "Why my jar has the weird date? You have the reproducible build. Ah, ok, ty". But also I switch from Gradle to Maven then if would be less differences in artifacts.

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[gnodet]

LGTM

[stokito]

Thank you!