remove non-ascii characters from invalid metric names in error message

[replay]

When a metric with a non-ascii characters gets received the input validation correctly rejects it, but depending on the invalid character the serialization of the generated error message can fail, for example:

2024/01/16 17:24:39 ERROR: [transport] [server-transport 0xc05a8c21a0] Failed to marshal rpc status: code:400 message:"received a series with invalid metric name: 'invalid_metric_name_\xb0c' (err-mimir-metric-name-invalid)\n" details:{type_url:"type.googleapis.com/httpgrpc.HTTPResponse" value:"\x08\x90\x03\x12)\n\x0cContent-Type\x12\x19text/plain; charset=utf-8\x12!\n\x16X-Content-Type-Options\x12\x07nosniff\x1a\x80\x01received a series with invalid metric name: 'invalid_metric_name_\xb0c' (err-mimir-metric-name-invalid)\n"}, error: string field contains invalid UTF-8

This change removes the non-ascii characters from the metric name when generating the invalid metric name error message. It appends the string (non-ascii characters removed) to the modified metric name in the error message because if we'd just return the cleaned up string as part of the error message then the user who's looking at the error might not understand what the problem was.

[aknuds1]

LGTM

[pstibrany]

This change removes the non-ascii characters from the metric name when generating the invalid metric name error message.

If this removes all characters, what's left is useless. :( Could we skip only invalid utf-8 "characters"?