runtime: tests failing epically with LANG='C.UTF-8' on Alpine

Since Alpine/musl-linux does not really have locale like glibc based distributions, this inherently default. However, when set explicitly, many tests do fail with strange errors:

for example Microsoft.VisualBasic.Core.Tests

System.InvalidCastException : Conversion from string \"false\" to type 'Boolean' is not valid.
---- System.FormatException : Input string was not in a correct format.

related to dotnet/corefx#35646 and dotnet/corefx#32250

According to discussion in dotnet/corefx#32250, this is “expected”. We should update tests so they do not fail with default system setting. I also tried same setting on Ubuntu 18.04 and I don’t see same results. This should be investigated.

cc: @MattGal @ulisesh