trie: remove parameter 'fromLevel' in Prove (#27512)

This removes the feature where top nodes of the proof can be elided.
It was intended to be used by the LES server, to save bandwidth 
when the client had already fetched parts of the state and only needed
some extra nodes to complete the proof. Alas, it never got implemented
in the client.

tests/fuzzers/rangeproof/rangeproof-fuzzer.go

@@ -113,10 +113,10 @@ func (f *fuzzer) fuzz() int {
 			break
 		}
 		proof := memorydb.New()
-		if err := tr.Prove(entries[start].k, 0, proof); err != nil {
+		if err := tr.Prove(entries[start].k, proof); err != nil {
 			panic(fmt.Sprintf("Failed to prove the first node %v", err))
 		}
-		if err := tr.Prove(entries[end-1].k, 0, proof); err != nil {
+		if err := tr.Prove(entries[end-1].k, proof); err != nil {
 			panic(fmt.Sprintf("Failed to prove the last node %v", err))
 		}
 		var keys [][]byte

tests/fuzzers/trie/trie-fuzzer.go

@@ -187,7 +187,7 @@ func runRandTest(rt randTest) error {
 				return errors.New("hash mismatch in opItercheckhash")
 			}
 		case opProve:
-			rt[i].err = tr.Prove(step.key, 0, proofDb{})
+			rt[i].err = tr.Prove(step.key, proofDb{})
 		}
 		// Abort the test on error.
 		if rt[i].err != nil {