Rename flag wal_db_journalmode

This flag was defined as a regular flag and then was later changed to a
fixed_read_only flag.  This scenario is currently "unsupported" by the
flags infrastructure; an error occurs when trying to advance the flag to
staging. Work around this by renaming the flag so that the flags
infrastructure sees it as an entirely new flag. This cl adds this flag
to the legacykeystore code as well.

Bug: 296464083
Bug: 311648623
Test: m keystore2
Change-Id: If62a5fac2404113ca0bbc0807f154401c4241bf1
diff --git a/keystore2/src/database.rs b/keystore2/src/database.rs
index 63dbf7f..93de484 100644
--- a/keystore2/src/database.rs
+++ b/keystore2/src/database.rs
@@ -1036,7 +1036,7 @@
             break;
         }
 
-        if keystore2_flags::wal_db_journalmode() {
+        if keystore2_flags::wal_db_journalmode_v2() {
             // Update journal mode to WAL
             conn.pragma_update(None, "journal_mode", "WAL")
                 .context("Failed to connect in WAL mode for persistent db")?;