Enable GTS DA

[yuanxue2870]

Describe your changes

Summarise all code changes included in PR:
All edits are made in the DA_update submodule, which include:
1.Fix bugs for $WINLEN
2.Correct typos in the do_landDA.sh
3.Add Jiarui's current GTS yaml and add the elevation check (to be consistent with GHCN.yaml filters)
4.Enable 6-hr cycle for GTS DA

List any associated PRs in the submodules.
NOAA-PSL/land-DA_update#25

Issue ticket number and link

List the git Issue that this PR addresses:
#36

Test output

Is this PR expected to pass the DA_IMS_test (ie., does it change the output)?
Yes
Does it pass the DA_IMS_test?
Yes
If changes to the test results are expected, what are these changes? Provide a link to the output directory when running the test:
N/A

Checklist before requesting a review

• My branch being merged is up to date with the latest develop.
• I have performed a self-review of my code by examining the differences that will be merged.
• I have not made any unnecessary code changes / changed any default behavior.
• My code passes the DA_IMS_test, or differences can be explained.

[yuanxue2870]

Please review: @ClaraDraper-NOAA @jiaruidong2017, Thank you!