Update version when bulk param is available in ES stats API

[ycombinator]

What does this PR do?

Updates the minimum version of Elasticsearch that allows the GET _stats API to accept the bulk parameter.

Why is it important?

Elasticsearch added the new bulk parameter to the GET _stats API in elastic/elasticsearch#52208. That PR has been merged so this parameter is available in master / 8.0.0 of Elasticsearch. However, that PR has not yet been backported (see elastic/elasticsearch#55447), so this parameter is not available in earlier versions of Elasticsearch yet.

So for now we tell the elasticsearch Metricbeat module to only add the bulk parameter to the GET _stats API call request if the version of Elasticsearch it's talking to is 8.0.0 or higher.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works Parity tests should start passing once this PR is merged.
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc. The feature that introduced this bug will be released in 7.8.0. Since that hasn't yet been released yet, no CHANGELOG entry for the bugfix is necessary.

[elasticmachine]

Pinging @elastic/integrations-services (Team:Services)

[elasticmachine]

Pinging @elastic/stack-monitoring (Stack monitoring)

[chrisronline]

LGTM

[elasticmachine]

💚 Build Succeeded

Expand to view the summary

Build stats

• Build Cause: [Pull request Update version when bulk param is available in ES stats API #18459 updated]

• Start Time: 2020-05-13T21:36:35.426+0000

• Duration: 68 min 8 sec (4088430)

Test stats 🧪

Test	Results
Failed	0
Passed	3022
Skipped	756
Total	3778

[ycombinator]

run tests