fix(dev): fix Rust toolchain check in Makefile (#18218)

The `make` command inside of the Vector environment image optimizes `$(shell ...)` such that if the
command to run is simple enough, it will just call it directly without using a shell. The problem is
that the `command` command used to check if the Rust toolchain is installed is a shell builtin and,
when optimized, `make` invocations that use the `check-build-tools` target emit the following error:

    make: command: Command not found

This commit fixes the issue by using a redirect, and thus forcing `make` to use the shell.

Ref: https://stackoverflow.com/a/12991757

Signed-off-by: Hugo Hromic <hhromic@gmail.com>