fix: grpc-alts is used not only in tests (#761)

* fix: grpc-alts is used not only in tests

This reverts commit c8ef46f.

* fix: adds grpc-alts as compile time dependency

* fix: removes duplicate dependency

Removes duplicate grpc-alts dependency

google-cloud-spanner/pom.xml

@@ -246,6 +246,11 @@
       <groupId>com.google.auth</groupId>
       <artifactId>google-auth-library-credentials</artifactId>
     </dependency>
+    <!-- Dependency for DirectPath -->
+    <dependency>
+      <groupId>io.grpc</groupId>
+      <artifactId>grpc-alts</artifactId>
+    </dependency>
 
     <!-- Test dependencies -->
     <dependency>
@@ -254,13 +259,6 @@
       <scope>test</scope>
     </dependency>
 
-    <!-- Test dependency for DirectPath -->
-    <dependency>
-      <groupId>io.grpc</groupId>
-      <artifactId>grpc-alts</artifactId>
-      <scope>test</scope>
-    </dependency>
-
     <!-- Need testing utility classes for generated gRPC clients tests -->
     <dependency>
       <groupId>com.google.api</groupId>