Adds dependency on google-cloud bom (#1034)

* Depend on shaded spanner

* Use google-cloud bom

Author: vkedia

spanner/cloud-client/pom.xml

@@ -40,7 +40,6 @@ limitations under the License.
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-spanner</artifactId>
-      <version>0.34.0-beta</version>
       <exclusions>
         <exclusion>
           <groupId>com.google.guava</groupId>
@@ -78,17 +77,37 @@ limitations under the License.
         <groupId>io.opencensus</groupId>
         <artifactId>opencensus-exporter-trace-stackdriver</artifactId>
         <version>${opencensus.version}</version>
+        <exclusions>
+          <exclusion>
+            <groupId>com.google.cloud</groupId>
+            <artifactId>google-cloud-trace</artifactId>
+          </exclusion>
+        </exclusions>
     </dependency>
     <dependency>
         <groupId>io.opencensus</groupId>
         <artifactId>opencensus-exporter-stats-stackdriver</artifactId>
         <version>${opencensus.version}</version>
+        <exclusions>
+          <exclusion>
+            <groupId>com.google.cloud</groupId>
+            <artifactId>google-cloud-monitoring</artifactId>
+          </exclusion>
+        </exclusions>
     </dependency>
     <dependency>
         <groupId>io.opencensus</groupId>
         <artifactId>opencensus-contrib-grpc-metrics</artifactId>
         <version>${opencensus.version}</version>
     </dependency>
+    <dependency>
+      <groupId>com.google.cloud</groupId>
+      <artifactId>google-cloud-trace</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>com.google.cloud</groupId>
+      <artifactId>google-cloud-monitoring</artifactId>
+    </dependency>
 
     <!-- Test dependencies -->
     <dependency>
@@ -103,9 +122,18 @@ limitations under the License.
       <version>0.39</version>
       <scope>test</scope>
     </dependency>
-
   </dependencies>
-
+  <dependencyManagement>
+    <dependencies>
+      <dependency>
+        <groupId>com.google.cloud</groupId>
+        <artifactId>google-cloud-bom</artifactId>
+        <version>0.34.0-alpha</version>
+        <type>pom</type>
+        <scope>import</scope>
+      </dependency>
+    </dependencies>
+  </dependencyManagement>
   <build>
     <plugins>
       <plugin>