group-allowlist&group-denylist for notifier doesn't make impact

I'm trying to use different email notifier per consumer group prefix and therefore I have to use group-allowlist and group-denylist.

**Problem description**
For the beginning this is my notifier configs:
```
[notifier.email-crmtgroup-1111]
class-name="email"
interval=60
threshold=3
send-close=true
send-once=true
group-allowlist="ˆ(crmgroup-1111|crmgroup2-1111).*$"
group-denylist=""
template-open="/path/to/template.tmpl"
template-close="/path/to/template.tmpl"
server="localhost"
port=25
from="test"
to="some.email@email.domain"
```

_Burrow version: 1.3.4_

Now, I have tried multiple combinations for _group-denylist_ and _group-allowlist_ and these are:

1. group-denylist="ˆ(?!crmgroup-1111|crmgroup2-1111).*$", group-allowlist=""
2. group-denylist="", group-allowlist="ˆ(crmgroup-1111|crmgroup2-1111).*$"
3. group-denylist="", group-allowlist="ˆcrmgroup-1111.*$"

and couple of more but these are most important. Whichever combination I used I get error email if consumer-group `test-group` is having a problems. I'm not sure whether I'm mistaking somewhere or these two configs have zero impact.

Anyone met with something similar?

Start by reproducing the notifier configuration with the listed group-allowlist and group-denylist combinations against the reported consumer groups. Check the notifier's filtering behavior and configuration parsing; this is done when test-group no longer triggers an email while the intended crmgroup-1111 or crmgroup2-1111 groups still do.

Written by the indexing model from the issue text.