sanity.external test fails consistently while running rm -f

**Summary**

sanity.external is now failing consistently due to the error detailed below.

@smlambert - Could you please tag the person who owns these tests? Thank you. :)

**Details**

Last pass:
16:46:42 openjdk version "11.0.20.1" 2023-08-24
16:46:42 OpenJDK Runtime Environment Temurin-11.0.20.1+1 (build 11.0.20.1+1)
16:46:42 OpenJDK 64-Bit Server VM Temurin-11.0.20.1+1 (build 11.0.20.1+1, mixed mode)
https://ci.adoptium.net/job/Test_openjdk11_hs_sanity.external_x86-64_linux/599/consoleFull

First failure:
18:26:49 openjdk version "11.0.21-beta" 2023-10-17
18:26:49 OpenJDK Runtime Environment Temurin-11.0.21+4-202308261707 (build 11.0.21-beta+4-202308261707)
18:26:49 OpenJDK 64-Bit Server VM Temurin-11.0.21+4-202308261707 (build 11.0.21-beta+4-202308261707, mixed mode)
https://ci.adoptium.net/job/Test_openjdk11_hs_sanity.external_x86-64_linux/600/console

Example failure:
https://ci.adoptium.net/job/Test_openjdk11_hs_sanity.external_x86-64_linux/601/console

```
18:41:51 [exec] Reading package lists...
18:41:51 [exec] E: Problem executing scripts APT::Update::Post-Invoke 'rm -f /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin || true'
18:41:51 [exec] E: Sub-process returned an error code
18:41:52 [exec] The command '/bin/sh -c apt-get update && apt-get install -qq -y --no-install-recommends software-properties-common && apt-get install -qq -y --no-install-recommends gnupg && add-apt-repository ppa:ubuntu-toolchain-r/test && apt-get update && apt-get install -y --no-install-recommends git wget tar && rm -rf /var/lib/apt/lists/*' returned a non-zero code: 100
18:41:52 [exec] 
18:41:52
18:41:52 BUILD FAILED
```

Start with the linked sanity.external CI console logs, comparing the last passing run with jobs 600 and 601, then reproduce the failing container command around apt-get update and its rm -f hook. Done means identifying and correcting the environment failure so the sanity.external job completes successfully.

Written by the indexing model from the issue text.