The ndk.dir local property has been deprecated for a while now and the recommended way to install the NDK is “side-by-side” where it is bundled within the SDK folder (see the first “note” on this page - https://developer.android.com/studio/projects/install-ndk).
If you need to specify a version of the NDK you can do so by using the android.ndkVersion setting in the build.gradle file. To do this in the Projucer you can use the “Extra module’s build.gradle content” setting in the Android exporter and in your case you’d add the following:
ndkVersion '22.0.7026061'