Saneamento definição :
conditions relating to public health, especially the provision of clean drinking water and adequate sewage disposal.
e Trabalhador de saneamento definição :
a person employed to collect, haul away, and dispose of garbage.
Então, sim, o saneamento tem a ver com a limpeza, incluindo o lixo e possivelmente até mesmo o esgoto. Para mais sobre o assunto, leia sobre O que faz um trabalhador de saneamento?
O wiki tem o seguinte:
After crash-landing on the planet, Finn revealed to Han and Chewie that he used to work on sanitation on Starkiller Base, much to Solo's annoyance. Finn devised a plan to lower the shield around the planet, which would allow the Resistance pilots to attack the oscillator and destroy the weapon. Chewbacca captured Captain Phasma, and the three forced her to lower the shield. She warned them that her troops would storm in and kill them all, but Solo asked Finn if there happened to be any convenient trash compactors in the base and they were able to dump her into one via garbage chute.
Presumivelmente, o passado de Finn no saneamento básico foi incluído para 1) ser bem-humorado e 2) permitir uma referência ao original Star Wars mencionando compactadores de lixo.
Um pôster no Quora
It's pretty clear Finn mentioned his MOS as Sanitation purely as a plot device.
Sanitation is a specialized engineering role responsible for water treatment and plumbing infrastructure.
It's used merely to explain away how Finn is familiar with all parts of the Starkiller Base, and is able to move from one location to another undetected by security.
And a homage to how in the original Luke et al escaped through the garbage disposal system.