ARROW-6406: [C++] Fix jemalloc URL for offline build in thirdparty/versions.txt

[wesm]

The archive URL is not the released tarball and did not work with jemalloc_ep

[kou]

+1

[codecov-io]

Codecov Report

Merging #5246 into master will increase coverage by 1.55%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #5246      +/-   ##
==========================================
+ Coverage   87.63%   89.18%   +1.55%     
==========================================
  Files        1033      750     -283     
  Lines      148630   107752   -40878     
  Branches     1437        0    -1437     
==========================================
- Hits       130249    96103   -34146     
+ Misses      18019    11649    -6370     
+ Partials      362        0     -362

Impacted Files	Coverage Δ
cpp/src/arrow/filesystem/s3_internal.h	95.12% <0%> (-4.88%)	⬇️
cpp/src/plasma/thirdparty/ae/ae.c	70.75% <0%> (-0.95%)	⬇️
js/src/util/fn.ts
go/arrow/memory/memory_avx2_amd64.go
rust/datafusion/src/execution/filter.rs
rust/arrow/src/csv/writer.rs
rust/datafusion/src/bin/main.rs
go/arrow/ipc/file_reader.go
js/src/builder/index.ts
rust/parquet/src/arrow/converter.rs
... and 276 more

---

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[codecov-io]

Codecov Report

Merging #5246 into master will increase coverage by 1.55%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #5246      +/-   ##
==========================================
+ Coverage   87.63%   89.18%   +1.55%     
==========================================
  Files        1033      750     -283     
  Lines      148630   107752   -40878     
  Branches     1437        0    -1437     
==========================================
- Hits       130249    96103   -34146     
+ Misses      18019    11649    -6370     
+ Partials      362        0     -362

Impacted Files	Coverage Δ
cpp/src/arrow/filesystem/s3_internal.h	95.12% <0%> (-4.88%)	⬇️
cpp/src/plasma/thirdparty/ae/ae.c	70.75% <0%> (-0.95%)	⬇️
js/src/util/fn.ts
go/arrow/memory/memory_avx2_amd64.go
rust/datafusion/src/execution/filter.rs
rust/arrow/src/csv/writer.rs
rust/datafusion/src/bin/main.rs
go/arrow/ipc/file_reader.go
js/src/builder/index.ts
rust/parquet/src/arrow/converter.rs
... and 276 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2164e3b...0c6c454. Read the comment docs.