boards/qemu*: add "prod" variants, not built by CircleCI as of now, to test Heads prod console output

[tlaurion]

Those basically turn off TRACING, DEBUGGING and PCAP output as opposed to their standard non -prod counterpart:

#Enable DEBUG output
#export CONFIG_DEBUG_OUTPUT=y
#export CONFIG_ENABLE_FUNCTION_TRACING_OUTPUT=y
#Enable TPM2 pcap output under /tmp
#export CONFIG_TPM2_CAPTURE_PCAP=y

This is to facilitate non-platform specific features in virtualized environment.
Note that :

• coreboot config still enables high verbosity kernel output, but once Heads is running, the output is similar to production for tpm1/tpm2/hotp/non-hotp variants.
• OEM only ship HOTP variants
• HOTP variants still not play well with qemu tcg mode (non-kvm/non-nested virt environements like QubesOS: can't fix).

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Will be used to develop #1822

[tlaurion]

Would be helpful to test all sorta things, including but not limited to #1203 when that happens both into flashrom/flashprog and qemu

[tlaurion]

Does not impact anything else, need it to provide output for #1849 for screenshots, merging