Merge 'fix/core/translate: ALTER TABLE DROP COLUMN: ensure schema cookie is updated even when target table is empty' from Jussi Saurio

Closes #2431
Discovered while fuzzing #2086
## What
We update `schema_version` whenever the schema changes
## Problem
Probably unintentionally, we were calling `SetCookie` in a loop for each
row in the target table, instead of only once at the end. This means 2
things:
- For large `n`, this is a lot of unnecessary instructions
- For `n==0`, `SetCookie` doesn't get called at all -> the schema won't
get marked as having been updated -> conns can operate on a stale schema
## Fix
Lift `SetCookie` out of the loop

Reviewed-by: Preston Thorpe <preston@turso.tech>

Closes #2432

core/translate/alter.rs

@@ -139,12 +139,6 @@ pub fn translate_alter_table(
                             dest_reg: record,
                             index_name: None,
                         });
-                        program.emit_insn(Insn::SetCookie {
-                            db: 0,
-                            cookie: Cookie::SchemaVersion,
-                            value: schema.schema_version as i32 + 1,
-                            p5: 0,
-                        });
 
                         program.emit_insn(Insn::Insert {
                             cursor: cursor_id,
@@ -155,6 +149,13 @@ pub fn translate_alter_table(
                         });
                     });
 
+                    program.emit_insn(Insn::SetCookie {
+                        db: 0,
+                        cookie: Cookie::SchemaVersion,
+                        value: schema.schema_version as i32 + 1,
+                        p5: 0,
+                    });
+
                     program.emit_insn(Insn::ParseSchema {
                         db: usize::MAX, // TODO: This value is unused, change when we do something with it
                         where_clause: None,