greetings,

It is good that you have your stance clear from the start that you are not aiming for campus placements and such which makes the decision easier;

think on these terms:

- Which branch will be the least time consuming?

So that you get the maximum time possible for your government jobs preparations. In this regard, I'd say metallurgy is more laid back than civil in terms of syllabus, civil also includes many calculation subjects and drawing subjects which can get tricky if you are not paying attention.

- Which branch will act as the best back up plan later?

here, civil wins over metallurgy for the simple reason of being a popular core branch since time immemorial. Civil graduates may not get much private sector opportunities but there are many government job openings at central and state level for civil students.

Civil is also a great branch for GATE and subsequent higher studies in the field.

Civil will also be a good placement backup as metallurgy students have a hard time during placements, it is an over all safe branch.

bottom line - go for metallurgy if you do not care for branch reputation or higher studies or do not need a back up option for jobs. otherwise, civil is a good option even for government jobs. (you can even opt for civil engg. as an optional in UPSC which has a decent success rate and low competition)

good day