files.block placement of temporary output file has flaws

[morrison12]

Describe the bug

1. There is a missing colon in what should be a fall-back to /tmp/ if TMPDIR is not set
2. As with Location of "askpass" file respects target's TMPDIR but not config.TEMP_DIR #1425, the fallback should be to config.TEMP_DIR not a hard-coded /tmp

To Reproduce

Consequence of #1425

Expected behavior

Temporary files should be put in the correct place.

Meta

System: Darwin
  Platform: macOS-14.7.7-arm64-arm-64bit
  Release: 23.6.0
  Machine: arm64
pyinfra: v3.4.1
  click: v8.2.1
  click: v8.2.1
  click: v8.2.1
  distro: v1.9.0
  gevent: v25.5.1
  jinja2: v3.1.6
  packaging: v25.0
  paramiko: v3.5.1
  python-dateutil: v2.9.0.post0
  pywinrm: v0.5.0
  typeguard: v4.4.4
  typing-extensions: v4.14.1
Executable: /Users/someone/.local/bin/pyinfra
Python: 3.12.11 (CPython, Clang 20.1.4 )

[Fizzadar]

Fixed via #1428