refactor(grids): move watermark register

[damyanpetev]

Related to #13562

While the use of the @__PURE__ notation is valid on a stand-alone expression call (I imagined it wouldn't be, but see https://github.com/javascript-compiler-hints/compiler-notations-spec/blob/main/pure-notation-spec.md, also https://esbuild.github.io/api/#pure) in this scenario it doesn't quite work.
The register is actually side-effectful to begin with and since this is a top level expression that doesn't have it's supposed return value used or exported the notation basically means permanent tree-shake and deletes the register.

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