Description of problem:

When it's defined a query to Loki in `Observe > Logs` containing ~=, the query is mutated when changed the `Time range`

Version-Release number of selected component (if applicable):

Logging 5.7
Logging 5.8

How reproducible:

Always

Steps to Reproduce:

1. Deploy ClusterLogging being the Log Store Loki
2. Log in into `OCP Console > Observe > Logs` and introduce a query containing ~= as it could be:

   { log_type="infrastructure", kubernetes_pod_name~=".*etcd.*" } | json
   

3. Change the time range from the default stablished from 1 hour for other
4. Review the query has changed

Actual results:

The original query:

{ log_type="infrastructure", kubernetes_pod_name~=".*etcd.*" } | json

is changed deleted automatically the ~, then, it doesn't match anymore pod name to check the logs. The query resultant is:

{ log_type="infrastructure", kubernetes_pod_name=".*etcd.*" } | json

Expected results:

The query remains the same after changing selecting a different Time range