Fix vsphere.datastore.capacity.used.pct value by removing *100

[kaiyan-sheng]

What does this PR do?

This PR is to change vsphere.datastore.capacity.used.pct from int64 to float64, make sure the value is between 0-1.

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
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Related issues

• Closes [Metricbeat] vsphere.datastore.capacity.used.pct with ECS format issue #23009

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Pinging @elastic/integrations-platforms (Team:Platforms)

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Build stats

• Build Cause: Pull request #23148 updated

• Start Time: 2020-12-15T19:36:09.749+0000

• Duration: 54 min 29 sec

Test stats 🧪

Test	Results
Failed	0
Passed	2295
Skipped	510
Total	2805

Steps errors

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Test stats 🧪

Test	Results
Failed	0
Passed	2295
Skipped	510
Total	2805