fix old atime ci

[tdhock]

This PR is an alternative to #7901.
old atime ci https://github.com/Rdatatable/data.table/actions/runs/34461127844/job/105616421290?pr=7899 was not able to install library(curl), required for library(gert), used instead of library(git2r) in new atime on CRAN yesterday.

[tdhock]

apt search curl says

libcurl4/now 7.68.0-1ubuntu2.25 amd64 [installed,local]
  easy-to-use client-side URL transfer library (OpenSSL flavour)
```
but sudo apt install libcurl4-openssl-dev says not found?

[tdhock]

I don’t think we can get this to work

[github-actions]

• HEAD=fix-old-atime-ci much faster for as.data.table.array improved in #7019
  

Generated via commit 0be5632

Download link for the artifact containing the test results: ↓ atime-results.zip

Task	Duration
R setup and installing dependencies	7 minutes and 8 seconds
Installing different package versions	13 minutes and 37 seconds
Running and plotting the test cases	6 minutes and 0 seconds