x/build: add LUCI linux-mipsle builder

[AaronGrand]

• Hostname: linux-mipsle-hooc-ag
• Certificate Request: linux-mipsle-hooc-ag.csr.txt

[dmitshur]

Thanks for requesting to add a builder to test the linux/mipsle port (CC @golang/mips). There's also issue #67304 tracking this. Is this meant to be an additional builder?

CC @golang/release, @prattmic.

[AaronGrand]

@dmitshur
Yes, this is intended to be an additional linux/mipsle builder, complementary to the one provided by CIP United.

This builder is running on native MIPS32 hardware (MediaTek MT7621) with a MIPS32 kernel and userspace, softfloat (no FPU), and OpenWrt.

We’re planning to run multiple identical machines behind the same hostname (linux-mipsle-hooc-ag) once the setup is validated.

[prattmic]

Here is the certificate: linux-mipsle-hooc-ag-1770314189.cert.txt

[AaronGrand]

@prattmic
Quick status update:
The builder is now online and idling correctly.
The bot starts automatically after reboot and reconnects successfully.