Fix generate-bytecode-expectations crash

https://codereview.chromium.org/2176143002 removed parsing of a golden
file header option but did not remove the option.

BUG=
LOG=n

Review-Url: https://codereview.chromium.org/2189583002
Cr-Commit-Position: refs/heads/master@{#38096}

test/cctest/interpreter/bytecode_expectations/Generators.golden

@@ -7,7 +7,6 @@ pool type: mixed
 execute: yes
 wrap: no
 test function name: f
-ignition generators: yes
 
 ---
 snippet: "