RFR: 8274864: Remove Amman/Cairo hacks in ZoneInfoFile

[Naoto Sato]

While working on tzdata2021c update, I noticed there is a dead code in `sun.util.calendar.ZoneInfoFile`, which was used to tweak the rules for `endOfDay` for certain cases. These are no longer needed as JDK's code is already capable of dealing with transitions beyond the end of the day.

-------------

Commit messages:
 - 8274864: Remove Amman/Cairo hacks in ZoneInfoFile

Changes: https://git.openjdk.java.net/jdk/pull/5857/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5857&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274864
  Stats: 29 lines in 1 file changed: 0 ins; 29 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5857.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5857/head:pull/5857

PR: https://git.openjdk.java.net/jdk/pull/5857