refactor(location)!: remove default_country definitions

[matthewmayer]

Removes the old default_country definition files

• Not currently used by any public method
• Not listed in LocationDefinition
• Not covered by any tests
• Avoids any potential arguments about "what is a country" (e.g. fixes Avoid political debate with disputed area's default_country.ts #2368), or which country should be listed for generic locales like ar or en which cover multiple countries

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.57%. Comparing base (5ef8ef1) to head (65a85de).

Additional details and impacted files

@@            Coverage Diff             @@
##             next    #2740      +/-   ##
==========================================
+ Coverage   99.56%   99.57%   +0.01%     
==========================================
  Files        3034     2974      -60     
  Lines      250453   250273     -180     
  Branches      981      983       +2     
==========================================
- Hits       249367   249215     -152     
- Misses       1057     1058       +1     
+ Partials       29        0      -29     

Files	Coverage Δ
src/locales/af_ZA/location/index.ts	100.00% <ø> (ø)
src/locales/ar/location/index.ts	100.00% <ø> (ø)
src/locales/az/location/index.ts	100.00% <ø> (ø)
src/locales/cs_CZ/location/index.ts	100.00% <ø> (ø)
src/locales/da/location/index.ts	100.00% <ø> (ø)
src/locales/de/location/index.ts	100.00% <ø> (ø)
src/locales/de_AT/location/index.ts	100.00% <ø> (ø)
src/locales/de_CH/location/index.ts	100.00% <ø> (ø)
src/locales/dv/location/index.ts	100.00% <ø> (ø)
src/locales/el/location/index.ts	100.00% <ø> (ø)
... and 50 more

... and 30 files with indirect coverage changes