Choose data source for visualization doesn't match on "-"

[Oofles]

**Kibana version: 7.9.1 (also seen in 7.8)

**Elasticsearch version: 7.9.1

**Server OS version: Replicating on demo.elastic.co

**Browser version: Chrome v. 86 (64-bit)

**Browser OS version: Windows 10

**Original install method (e.g. download page, yum, from source, etc.): Replicating on demo.elastic.co

**Describe the bug:

• When creating a new visualization and selecting the source data, the "-" character will not match on index patterns. From testing, it looks like the index patterns are matching on space vs. the dash character as they are displayed and created. This can be replicated in the demo elastic environment (demo.elastic.co), but I've seen the same issue in production environments running 7.8 and later.

Steps to reproduce:

1. Create new visualization
2. Select data table (or any other)
3. Attempt to type an existing index pattern with a "-" and you will get 0 results

**Expected behavior:

• I would expect "-" to match on existing index patterns (e.g. searching for "discourse-" to match "discourse-users" and "discourse-metrics-*"

Screenshots (if relevant):

**Errors in browser console (if relevant): N/A

**Provide logs and/or server output (if relevant): N/A

**Any additional context: N/A

[nreese]

closing, duplicate of #5734