Describe the bug
Regex selector filter should works exactly like Prometheus label matchers but it not.

the =~ and !~ regex operators are fully anchored.

So "1234" =~ "23.*" should return false, same as "1234" =~ ".*23".

Query

{foo="bar"}
{foo="bar"} | label_format test="1234" | test=~"1234"
{foo="bar"} | label_format test="1234" | test=~"23.*"
{foo="bar"} | label_format test="1234" | test=~".*23"

Expected behaviour
The first two queries should return all lines but last two queries return no lines.

Actual behaviour
All four queries return all lines.