chore: use java helper for templates

[chingor13]

We are cleaning up usage of common templates in synthtool. This allows us the cleanup usage in a centralized place rather than in 60+ repos

[codecov]

Codecov Report

Merging #220 into master will decrease coverage by 0.28%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master     #220      +/-   ##
============================================
- Coverage     82.21%   81.93%   -0.29%     
  Complexity      983      983              
============================================
  Files            99       99              
  Lines          6040     6040              
  Branches        332      318      -14     
============================================
- Hits           4966     4949      -17     
- Misses          897      899       +2     
- Partials        177      192      +15     

Impacted Files	Coverage Δ	Complexity Δ
...igtable/admin/v2/BaseBigtableTableAdminClient.java	58.29% <0.00%> (-4.03%)	50.00% <0.00%> (ø%)
...able/admin/v2/BaseBigtableInstanceAdminClient.java	60.20% <0.00%> (-3.15%)	56.00% <0.00%> (ø%)
...om/google/cloud/bigtable/emulator/v2/Emulator.java	56.52% <0.00%> (-2.61%)	14.00% <0.00%> (ø%)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 1c78d84...1ec3cdd. Read the comment docs.