SNOW-1855886 gracefully ignore when default region us-west-2 is used in DSN or NewConnector

[sfc-gh-dszmolka]

Description

us-west-2 region is the default region in Snowflake, and a special one. We already had checks for the case where someone accidentally configures it in Region, but for Account we did not have any, which led to an Account (mis)configured as myaccount.us-west-2 instead of omitting the region (as is the default) and using myaccount, not being able to connect to Snowflake and instead failing with HTTP404.

This change attempts to step over such simple misconfiguration gracefully and

• ignores the extra .us-west-2 from Account instead of allowing the connection to proceed, which then surely will fail on the Snowflake backend
• logs a line about the misconfiguration on Info level, giving it a chance for the user to notice and correct it

Checklist

• Created tests which fail without the change (if possible)
• Extended the README / documentation, if necessary

[codecov]

Codecov Report

Attention: Patch coverage is 63.63636% with 4 lines in your changes missing coverage. Please review.

Project coverage is 82.20%. Comparing base (45b3d45) to head (afc60ef).

Files with missing lines	Patch %	Lines
dsn.go	63.63%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1278      +/-   ##
==========================================
- Coverage   82.21%   82.20%   -0.02%     
==========================================
  Files          55       55              
  Lines       13537    13547      +10     
==========================================
+ Hits        11130    11136       +6     
- Misses       2407     2411       +4     

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