remove Flyway completely from Gradle build (fixes FINERACT-765)

we (of course), still, but only, run it in-App at runtime boot

This is a clean-up which removes something we don't actually need.

Most importantly, it unblocks the Gradle upgrade in FINERACT-700,
where this doesn't work anymore anyway (and while there's a fix
making it work on one of my branches, it seems simpler to just
remove it).

Dockerfile

@@ -26,7 +26,6 @@ RUN mkdir fineract
 COPY . fineract
 
 WORKDIR fineract
-RUN sed -i 's/localhost/fineractmysql/' ./fineract-provider/build.gradle
 RUN sed -i 's/localhost/fineractmysql/' ./fineract-provider/src/main/resources/sql/migrations/list_db/V1__mifos-platform-shared-tenants.sql
 RUN ./gradlew clean war
 RUN mv build/libs/fineract-provider.war /opt/bitnami/tomcat/webapps