fix: prevent clean task from deleting project sources (#2342)

* fix: update clean task to delete buildDirectory instead of projectDirectory

* fix: update deprecated rootProject.buildDir to layout.buildDirectory in tutorials

ApiDemos/project/build.gradle.kts

@@ -40,5 +40,5 @@ allprojects {
 }
 
 tasks.register<Delete>("clean") {
-    delete(rootProject.layout.projectDirectory)
+    delete(rootProject.layout.buildDirectory)
 }

tutorials/java/CurrentPlaceDetailsOnMap/build.gradle.kts

@@ -39,5 +39,5 @@ allprojects {
 }
 
 tasks.register<Delete>("clean") {
-    delete(rootProject.buildDir)
+    delete(rootProject.layout.buildDirectory)
 }

tutorials/java/MapWithMarker/build.gradle.kts

@@ -35,5 +35,5 @@ allprojects {
 }
 
 tasks.register<Delete>("clean") {
-    delete(rootProject.buildDir)
+    delete(rootProject.layout.buildDirectory)
 }

tutorials/java/Polygons/build.gradle.kts

@@ -35,5 +35,5 @@ allprojects {
 }
 
 tasks.register<Delete>("clean") {
-    delete(rootProject.buildDir)
+    delete(rootProject.layout.buildDirectory)
 }

tutorials/kotlin/CurrentPlaceDetailsOnMap/build.gradle.kts

@@ -42,5 +42,5 @@ allprojects {
 }
 
 tasks.register<Delete>("clean") {
-    delete(rootProject.buildDir)
+    delete(rootProject.layout.buildDirectory)
 }

tutorials/kotlin/Polygons/build.gradle.kts

@@ -39,5 +39,5 @@ allprojects {
 }
 
 tasks.register<Delete>("clean") {
-    delete(rootProject.buildDir)
+    delete(rootProject.layout.buildDirectory)
 }