util-docker: Remove 'latex/riscv64' as Docker build target

It is unlikely anyone will be running these images on a RISC-V system
anytime soon. They are costly in terms of space and also require
RISC-V emulation to build which is very slow. This change has it so our
multi-platform builds just target ARM and X86.

util/dockerfiles/docker-bake.hcl

@@ -37,9 +37,8 @@ variable "TAG" {
 
 # Common attributes across all targets. Note: these can be overwritten.
 target "common" {
-  # Here we are enabling multi-platform builds. We are compiling to ARM, X86,
-  # and RISC-V.
-  platforms = ["linux/amd64", "linux/arm64", "linux/riscv64"]
+  # Here we are enabling multi-platform builds. We are compiling to ARM, X86]
+  platforms = ["linux/amd64", "linux/arm64"]
   pull = true
 }