Remove `boolVariation` feature flag, and associated code branches

[shanman190]

This one is going to be a little tricky as we'll have to determine an effective way to pick which side of the evaluation should be lifted.

Case: true side should remain, false side should be removed Before:

import com.launchdarkly.sdk.LDContext;
import com.launchdarkly.sdk.server.LDClient;

class Test {
    public void a() {
        LDClient client = new LDClient("sdk-key");
        LDContext context = LDContext.builder("context-key")
                .name("user")
                .build();
        boolean flagValue = client.boolVariation("flag-key-123abc", context, false);
        if (flagValue) {
            // Application code to show the feature
        } else {
            // The code to run if the feature is off
        }
    }
}

After:

import com.launchdarkly.sdk.LDContext;
import com.launchdarkly.sdk.server.LDClient;

class Test {
    public void a() {
        LDClient client = new LDClient("sdk-key");
        LDContext context = LDContext.builder("context-key")
                .name("user")
                .build();
        // Application code to show the feature
    }
}

NOTE: There's an additional potential cleanup here if the LDContext or LDClient is no longer used within the current scope, those could be removed as well.

NOTE 2: inverse case should also be possible for a user. We won't be able to know without user input which side of the if to select.

[timtebeek]

We might be able to reuse Simplify constant if branch execution , by replacing the call to the client with a literal true or false, which would then get cleaned up as seen in this test.

[timtebeek]

We recently had some improvements to the existing recipe, such that we should be in an even better state to clean up dead code paths when we replace a flag with true or false.

• https://github.com/openrewrite/rewrite-static-analysis/pull/193

[timtebeek]

Figured give this a quick first go in

• https://github.com/openrewrite/rewrite-launchdarkly/pull/10

[timtebeek]

This one is implemented as set out above; there might be others to implement still for non boolean feature flag, but I suggest we raise separate issues for those to make it clear what has, and has not been picked up.