8383175: (tz) Update Timezone Data to 2026b

[gnu-andrew]

This is a clean backport of the two part tzdata2026b update. The comment changes were applied in one commit and the actual change in a follow-up, which are combined in this one PR to simplify backports to the update releases. I see similar being done in openjdk/jdk26u#186 and I've also done this in openjdk/jdk25u-dev#547

I'm opening this now to see if 21u has the same issues as 25u. So far my local testing suggests not, as 21u still has the COMPAT provider:

$ make -C ~/builder/21u-dev run-test TEST="jtreg:java/text/Format java/util/TimeZone sun/util/calendar sun/util/resources"
==============================
Test summary
==============================
   TEST                                              TOTAL  PASS  FAIL ERROR   
   jtreg:test/jdk/java/text/Format                     113   113     0     0   
   jtreg:test/jdk/java/util/TimeZone                    27    27     0     0   
   jtreg:test/jdk/sun/util/calendar                      5     5     0     0   
   jtreg:test/jdk/sun/util/resources                    22    22     0     0   
==============================
TEST SUCCESS

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Progress

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Issue

• JDK-8383175: (tz) Update Timezone Data to 2026b (Enhancement - P3)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk21u-dev.git pull/2904/head:pull/2904
$ git checkout pull/2904

Update a local copy of the PR:
$ git checkout pull/2904
$ git pull https://git.openjdk.org/jdk21u-dev.git pull/2904/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 2904

View PR using the GUI difftool:
$ git pr show -t 2904

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk21u-dev/pull/2904.diff

[bridgekeeper]

👋 Welcome back andrew! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

This backport pull request has now been updated with issue from the original commit.