Revert "SONARPLUGINS-3009 Use the new ProjectBootstrapper extension"

This reverts commit 01e82fe5902c081b9b32f84bcb4b6f277bfebb7c.

Conflicts:
	pom.xml
SONARPLUGINS-3009 Keep backward compatibility
ProjectReactor is still provided by SonarRunner for SonarQube older than 3.7