Refactor node selector configuration for ephemeral executor

[alfespa17]

Adding options to customize ephemeral executor using the following environment variables.

• EPHEMERAL_CONFIG_NODE_SELECTOR_TAGS
• EPHEMERAL_CONFIG_SERVICE_ACCOUNT
• EPHEMERAL_CONFIG_ANNOTATIONS

The EPHEMERAL_CONFIG_NODE_SELECTOR_TAGS and EPHEMERAL_CONFIG_ANNOTATIONS allow to have several values separated by a semicolon

For example this can be used at workspace level like the following:

Example:

[sonarcloud[bot]]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud