Append processor adds blank value by default

[lockewritesdocs]

Kibana version:
8.0.0 (SNAPSHOT)

Elasticsearch version:
8.0.0 (SNAPSHOT)

Server OS version:
macOS Catalina 10.15.6 (19G2021)

Browser version:
Chrome 84.0.4147.125

Original install method (e.g. download page, yum, from source, etc.):
https://snapshots.elastic.co/8.0.0-d196c3d2/downloads/kibana/kibana-8.0.0-SNAPSHOT-darwin-x86_64.tar.gz

Describe the bug:
When adding an append processor, the UI adds a blank value by default. If the user does not delete that blank value, it gets added to the specified field as a value.

Steps to reproduce:

1. Access Kibana. Go to Management > Stack Management.
2. Choose Ingest Node Pipelines.
3. Click Create a pipeline.
4. Click Add a processor, and then choose Append as the processor type.

Expected behavior:
All fields are blank and require input from the user.

Screenshots (if relevant):
The blank value is visible when selecting Append as the processor.

If the user does not delete the blank space, it is added as a value.

Any additional context:
This is the first bug that I've reported. I'm pretty sure it's valid!

[elasticmachine]

Pinging @elastic/es-ui (Team:Elasticsearch UI)

[TinaHeiligers]

I tried to reproduce the issue but it seems to have been fixed recently.

[cjcenizal]

@alisonelizabeth Could you take a look at this please?

[alisonelizabeth]

I'm not able to reproduce either. There have been some changes made to the form library recently, which may have resolved this (#75302). @lockewritesdocs can you retest with the latest from master and see if you're still able to reproduce?

[lockewritesdocs]

@alisonelizabeth, I just pulled a build from master that was built on August 21, and the issue seems to be resolved now. Thank you for investigating! I'll mark this one as closed.