[5102] Addressed review comments.

- Removed MySQL indexes added accidentally.
- Fixed a commentary in a DORA unit tests.

src/bin/dhcp4/tests/dora_unittest.cc

@@ -948,7 +948,8 @@ TEST_F(DORATest, reservationByCircuitId) {
 // client-id.
 TEST_F(DORATest, reservationByClientId) {
     Dhcp4Client client(Dhcp4Client::SELECTING);
-    // Use relay agent so as the circuit-id can be inserted.
+    // Use relay agent to make sure that the desired subnet is
+    // selected for our client.
     client.useRelay(true, IOAddress("10.0.0.20"), IOAddress("10.0.0.21"));
     // Specify client identifier.
     client.includeClientId("01:11:22:33:44:55:66");

src/share/database/scripts/mysql/dhcpdb_create.mysql

@@ -480,11 +480,6 @@ UPDATE schema_version
 SET version = '5', minor = '0';
 # This line concludes database upgrade to version 5.0.
 
-# Add indexes for lease tables which will be used to perform searches
-# for all leases by subnet id.
-CREATE INDEX lease4_subnet_id ON lease4 (subnet_id ASC);
-CREATE INDEX lease6_subnet_id ON lease6 (subnet_id ASC);
-
 # Add missing 'client-id' host identifier type.
 INSERT INTO host_identifier_type VALUES (3, 'client-id');