Bump effect and leanback minSdk to 19

These were overriding the previous minimum of 16 and therefore not
included in e54abaa75d.

PiperOrigin-RevId: 597242364

libraries/effect/build.gradle

@@ -16,7 +16,6 @@ android {
     namespace 'androidx.media3.effect'
 
     defaultConfig {
-        minSdkVersion 18
         // The following argument makes the Android Test Orchestrator run its
         // "pm clear" command after each test invocation. This command ensures
         // that the app's state is completely cleared between tests.

libraries/ui_leanback/build.gradle

@@ -16,8 +16,6 @@ apply from: "$gradle.ext.androidxMediaSettingsDir/common_library_config.gradle"
 android {
     namespace 'androidx.media3.ui.leanback'
 
-    defaultConfig.minSdkVersion 17
-
     publishing {
         singleVariant('release') {
             withSourcesJar()