feat(api-gateway): Introduce CUBEJS_DEFAULT_TIMEZONE env

[KSDaemon]

with default value of UTC

Check List

• Tests have been run in packages where changes have been made if available
• Linter has been run for changed code
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 54.64%. Comparing base (4c55cb1) to head (14cd04a).
⚠️ Report is 9 commits behind head on master.

Files with missing lines	Patch %	Lines
packages/cubejs-backend-shared/src/env.ts	0.00%	1 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (4c55cb1) and HEAD (14cd04a). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (4c55cb1)	HEAD (14cd04a)
cubesql	1	0

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #10178       +/-   ##
===========================================
- Coverage   83.29%   54.64%   -28.65%     
===========================================
  Files         244      214       -30     
  Lines       74180    16997    -57183     
  Branches        0     3471     +3471     
===========================================
- Hits        61786     9288    -52498     
+ Misses      12394     7209     -5185     
- Partials        0      500      +500     

Flag	Coverage Δ
cube-backend	54.64% <50.00%> (?)
cubesql	?

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