db: schema_tables: reindent
db: schema_tables: reindent

Following conversion to corotuines in fc91e90c5987, remove extra
indents and braces left to make the change clearer.

One variable had to be renamed since without the braces it
duplicated another variable in the same block.

Test: unit (dev)

Closes #9125

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla