fix: properly copy files from compose to elastic-package

[mdelapenya]

What does this PR do?

This PR reverts the SRC/TARGET file paths used to check and copy the kibana configs from our compose config dir when copying that kibana config to a newly created elastic-package profile.

The src file, which the code checks its existence, must always follow the kibana.config.yml file name, and the target file, where the code copies the src file to, must always follow the elastic-package naming-schema for the config: kibana.config.8x.yml for master or kibana.config.default.yml.

Why is it important?

Whenever an scenario is using a profile different than default, as we do in the preconfigured-policies feature file, the code will incorrectly check for the existence under the compose config dir of a '8x' file, which does not exist, causing in the following error thrown by elastic-package:

[2021-11-03T05:48:41.518Z] time="2021-11-03T05:48:40Z" level=info msg="Running kibana with preconfigured-policies profile"
[2021-11-03T05:48:46.816Z] time="2021-11-03T05:48:46Z" level=error msg="Error executing command" args="[run github.com/elastic/elastic-package stack up --daemon --verbose --version 8.1.0-2fdb91c4-SNAPSHOT --services elasticsearch,fleet-server,kibana -p preconfigured-policies]" baseDir=. command=go env="map[kibanaDockerNamespace:kibana kibanaProfile:preconfigured-policies kibanaVersion:8.1.0-2fdb91c4-SNAPSHOT stackPlatform:linux/amd64 stackVersion:8.1.0-2fdb91c4-SNAPSHOT]" error="exit status 1" stderr="2021/11/03 05:48:46  WARN CommitHash is undefined, in both /var/lib/jenkins/workspace/master-1926-cab5847d-fcd3-40ed-8bc3-57f46e878e9f/.elastic-package/version and the compiled binary, config may be out of date.\n2021/11/03 05:48:46 DEBUG Enable verbose logging\n2021/11/03 05:48:46 DEBUG Distribution built without a version tag, can't determine release chronology. Please consider using official releases at https://github.com/elastic/elastic-package/releases\nBoot up the Elastic stack\nError: preconfigured-policies is not a valid profile, known profiles are: [default]\nexit status 1\n"

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 run the Unit tests (make unit-test), and they are passing locally
• I have run the End-2-End tests for the suite I'm working on, and they are passing locally
• I have noticed new Go dependencies (run make notice in the proper directory)

Related issues

• Caused by fix: use proper elastic-package's kibana config file #1738

Follow-ups

Backports must be fixed, as when backporting this PR to any maintenance branch, the elastic_package.go:L114 must be updated to kiban.config.default.yml.

[elasticmachine]

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• Start Time: 2021-11-03T06:49:38.640+0000

• Duration: 42 min 2 sec

• Commit: 083d9db

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Passed	248
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Total	248

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