v3dv: don't emit the subpass RCL for jobs that have emitted their own

This fixes multi-layer vkCmdClearAttachments CTS tests. The underlying
problem here is that even though this command runs inside a render pass,
it is implemented as a separate job that emits its own RCL to program
render target color clears, so we should not emit the subpass RCL for it.

Fixes 250+ CTS tests (all but a1r5g5b5) in:
dEQP-VK.api.image_clearing.core.clear_color_attachment.cube_layers.*
dEQP-VK.api.image_clearing.core.clear_color_attachment.multiple_layers.*
dEQP-VK.api.image_clearing.core.clear_depth_stencil_attachment.multiple_layers.*

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6766>
2 files changed