Remove extraneous check for Eager mode (#17125)

The check is already made once at the start of the method

Author: chrisyeh96

tensorflow/python/ops/control_flow_ops.py

@@ -178,8 +178,6 @@ def true_assert():
             condition, data, summarize, name="Assert")
 
       guarded_assert = cond(condition, no_op, true_assert, name="AssertGuard")
-      if context.in_eager_mode():
-        return
       return guarded_assert.op