auto complete should not ignore meta tags if they are also metric tags

[replay]

This PR is just undoing what was supposed to be a performance optimization.

Fixes: #1648

Tested with this scenario:

Created two metrics with fakemetrics:

• some.id.of.a.metric.1;anothertag=somelongervalue
• some.id.of.a.metric.2

Created meta record:

{
  "metaTags": [
    "anothertag=metavalue"
  ],
  "expressions": [
    "name=some.id.of.a.metric.2"
  ]
}

Using master, I call the autoComplete endpoint and get a result for the metric ending in .1 (metric tag) but not for the one ending with .2 (meta tag):

$ curl -s http://localhost:6070/tags/autoComplete/values -H 'Content-Type: json' -d '{"tag": "anothertag", "expr": ["name=some.id.of.a.metric.1"]}'  | jq
[
  "somelongervalue"
]
$ curl -s http://localhost:6070/tags/autoComplete/values -H 'Content-Type: json' -d '{"tag": "anothertag", "expr": ["name=some.id.of.a.metric.2"]}'  | jq
[]

Using this branch, I do the same two calls one more time, and now i get a result for both of them:

$ curl -s http://localhost:6070/tags/autoComplete/values -H 'Content-Type: json' -d '{"tag": "anothertag", "expr": ["name=some.id.of.a.metric.1"]}'  | jq
[
  "somelongervalue"
]
$ curl -s http://localhost:6070/tags/autoComplete/values -H 'Content-Type: json' -d '{"tag": "anothertag", "expr": ["name=some.id.of.a.metric.2"]}'  | jq
[
  "metavalue"
]

They can also be mixed in a single call:

$ curl -s http://localhost:6070/tags/autoComplete/values -H 'Content-Type: json' -d '{"tag": "anothertag", "expr": ["name=~some.id.of.a.metric.[12]"]}'  | jq
[
  "metavalue",
  "somelongervalue"
]

[Dieterbe]

This PR is just undoing what was supposed to be a performance optimization.

is this reverting a specific PR or commit? which one? do we know the performance ramifications?