Clean up gradle build file

[atomfrede]

Overview of the feature request

With the latest micronaut gradle plugin manual configuration for incremental compilation is not required anymore. We should remove it.

This (we already have) and replaces

micronaut {
    runtime "netty"
    testRuntime "junit5"
    processing {
        incremental true
        annotations "<%= packageName %>.*"
    }
}

tasks.withType(JavaCompile) {
    options.encoding = "UTF-8"
    options.compilerArgs.addAll([
        '-parameters',
        // enables incremental compilation
        '-Amicronaut.processing.incremental=true',
        '-Amicronaut.processing.annotations=<%= packageName %>.*',
        "-Amicronaut.processing.group=$project.group",
        "-Amicronaut.processing.module=$project.name",
    ])
}

Furthermore the custom config for continuous compilation we have in the dev profile can be removed I think (need to make sure the profiles are set correctly so maybe we need to keep it or parts of it). See what the application plugin sets: https://github.com/micronaut-projects/micronaut-gradle-plugin/blob/ce80195d88e78cbf2d69d3fe49fb491545aa3a94/src/main/java/io/micronaut/gradle/MicronautApplicationPlugin.java#L116

**tasks.withType(JavaExec) {
    classpath += configurations.developmentOnly
    jvmArgs('-XX:TieredStopAtLevel=1', '-Dcom.sun.management.jmxremote')
    if (System.getProperty("micronaut.environments")) {
        jvmArgs += '-Dmicronaut.environments=' + profiles + ',' + System.getProperty("micronaut.environments")
    } else {
        jvmArgs += '-Dmicronaut.environments=' + profiles
    }
    if (gradle.startParameter.continuous) {
        systemProperties(
            'micronaut.io.watch.restart':'true',
            'micronaut.io.watch.enabled':'true',
            "micronaut.io.watch.paths":"src/main"
        )
    }
}**

Motivation for or Use Case

Try not to move far away from what https://micronaut.io/launch creates

Related issues or PR

None.

[mraible]

@atomfrede Are you still interested in fixing this?