feat(hub): Remove startSpan method

Author: AbhiPrasad

packages/hub/src/hub.ts

@@ -384,13 +384,6 @@ export class Hub implements HubInterface {
     }
   }
 
-  /**
-   * @inheritDoc
-   */
-  public startSpan(context: SpanContext): Span {
-    return this._callExtensionMethod('startSpan', context);
-  }
-
   /**
    * @inheritDoc
    */

packages/types/src/hub.ts

@@ -180,11 +180,6 @@ export interface Hub {
   /** Returns all trace headers that are currently on the top scope. */
   traceHeaders(): { [key: string]: string };
 
-  /**
-   * @deprecated No longer does anything. Use use {@link Transaction.startChild} instead.
-   */
-  startSpan(context: SpanContext): Span;
-
   /**
    * Starts a new `Transaction` and returns it. This is the entry point to manual tracing instrumentation.
    *