[VMware]:change default max wait time to 15s for better performance, …

[xiaofengw1205]

…modify documentation about how to change default value

summary: change default max wait time to 15s

If cloud-init is enabled on VMware platform, cloud-init will wait until its configuration file is ready and currently the max wait is 90 seconds by default. With our test, this configuration file should be ready within 1 second, so change it to 15 seconds for better performance. Also update the documentation about how to change the default value in cloud-init configuration file.

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

[xiaofengw1205]

Hi all,
Please help to review when you have time. Thanks a lot.

[TheRealFalcon]

I'm a little wary of changing default wait times as it could cause regressions for a small number of people, but since the setting is configurable and we've added documentation for the setting, I'm +1.