ML allow aliased .ml-anomalies* index on PUT Job

[benwtrent]

Manually tested in the following manner:

• Created and opened A job
• Created a new index with the same mappings, aliases and properties as the .ml-anomalies-shared index
• Reindexed .ml-anomalies-shared into new index
• DELETE .ml-anomalies-shared
• Created alias for .ml-anomalies-shared to point to new concrete index.
• Created and opened a new job that needs the shared index.

After the test

GET _cat/aliases?v

alias                     index                           filter routing.index routing.search
.ml-annotations-read      .ml-annotations-6               -      -             -
.ml-annotations-write     .ml-annotations-6               -      -             -
.kibana                   .kibana_1                       -      -             -
.ml-anomalies-.write-jb2  .reindex-6-.ml-anomalies-shared -      -             -
.ml-anomalies-.write-job1 .reindex-6-.ml-anomalies-shared -      -             -
.ml-anomalies-jb2         .reindex-6-.ml-anomalies-shared *      -             -
.ml-anomalies-job1        .reindex-6-.ml-anomalies-shared *      -             -
.ml-anomalies-shared      .reindex-6-.ml-anomalies-shared -      -             -
.ml-state-write           .ml-state                       -      -             -

closes #38773

[elasticmachine]

Pinging @elastic/ml-core

[droberts195]

LGTM

Thanks for fixing this @benwtrent. I looked through all the other usages of Job.getInitialResultsIndexName and I cannot see another place where it would matter whether the name it returns is an index or an alias.